I have had BOTH XM AND Sirius in my vehicle and in the house for about 6 months. Sirius has superior sound quality -- MP3 or near CD quality -- while XM sounds more like a strong, clear FM radio signal. So Sirius has more sound fidelity and "presence." But for areas with lots of obstructions like where we live here in heavily wooded mountains, XM is much better. Sirius cuts out a LOT in wooded areas while XM only cuts out occasionally. IMO Sirius has better blues and country programming, while XM has better techno, rock, jazz, and pop programming. Except with Blues and Country, Sirius tends to repeat their stuff more because they lean towards music that gets more FM radio airtime, while XM tends to take more risks and play more variety and more selections that don't typically make it onto FM radio. Sirius has more balanced talk show programming - both liberal, moderate, and conservative, while XM has more conservative talk show programming because it’s owned in large part by Clear Channel. Interestingly, this doesn’t seem to affect their music and comedy programming. In contrast, Sirius carries both NPR and Wisdom stations. So if you want to avoid supporting right wing conservatives, stick with Sirius! We don't listen to sports so I can't tell you which is better in that category. But I read that Sirius just cut a deal with the NFL that will give them more pro football coverage than XM.

The portable Audiovox unit for Sirius is superior to the portable Delphi XM unit in a number of ways, so for home and portable use, Sirius has better equipment. But XM offers more types of XM-ready car audio equipment. I have a Kenwood Sirius-ready car head unit with a separate Kenwood adaptor that enables me to run the Delphi XM car base unit into the AUX port on the head unit. This gives me both in my car so I can switch back and forth between them based on reception quality and what's playing. I love the variety possible with this both in my car and home.

So if I had to choose only one, I would go with XM based on where we live and the kind of music we listen to. But Sirius is a better choice if you live in a more open area and want better sounding music. The extra $3 per month is so little compared to other things - just one burger or Starbucks.

One thing is certain - there is NO comparison between FM radio and satellite radio. I never listen to FM any more since satellite is so superior in sound quality, music selection, and NO COMMERCIALS! Get satellite radio for your home, vehicle, RV, and boat. If you get one of the portable units and install base units in more than one location, you can swap it between different locations, while still paying a single subscription fee. But if you can afford an extra 10-13 bucks per month and a few hundred dollars more up front, subscribing to BOTH XM and Sirius is a fabulous way to enjoy an unlimited variety of programming, including the specials and exclusives on both. I’m really surprised I haven’t encountered more people who have chosen to subscribe to both, since the extra cost is so little compared to most things people subscribe to such as cable or satellite TV.

clear channel is ultra liberal, not conservative.

I have had both XM and Sirius for over a year. I have to say that it is XM that has the superior sound quality, especially on the jazz and classical stations. Sirius compresses their music too much and background "noise" can easily be heard...not so on the XM. Sirius blows XM out of the water when it comes to sports coverage however,...they have the big "3 letter words" NFL, NBA, and NHL. Another side note on the music...XM has a substantially larger music library than Sirius. You are much less likely to hear repeats on XM. That said, you may/may not like the random playability that XM has over Sirius.

If ABC news and FOX news and CNN News can all be on BOTH formats, why can't HOWARD STERN?

I would much rather listen to Opie & Anthony than Howard Stern... just a personal preference, but who knows, things could change, January 1, 2006 is a long way off. Stinky rules!

I have to amend my earlier comments about the political leanings of XM. I must have been in a particularly surly mood when I posted this. I apologize for politicizing what should have been a review of the two stations not a chance to get on a political soapbox. Since I posted this, I have found that XM is quite liberal in its political leanings, including playing "We Gotta Beat Bush" several times a day on different stations. I based my comments about Clear Channel on a review I read myself when I was trying to decide between the two when I first was considering satellite radio. I should do more homework before spouting off.

But my technical review of the two still stands, at least as far as my equipment is concerned. I notice that another post says they get better sound quality on XM, so it looks like it varies by equipment more than signal. But every post I have read on XM fansites mentions the weak signal XM puts out. On both my home and car systems, I have to turn up the volume 4-5 db when I switch from Sirius to XM. I'm no sound engineer, but I do know that the signal to noise ratio affects signal quality, so that alone gives Sirius the edge in signal quality. I also read a review somewhere by some techie about the better Sirius compression. Again, I'm no engineer, but I do know what I hear, and on my home and car systems, Sirius has a distinctly better sound. btw - Both my home and car systems are high end systems!

But I totally agree about the high degree of repetition on Sirius. It is the single biggest down side of Sirius. I have come close to cancelling my two Sirius subscriptions, or at least one of them, many times because of the repetition. If you listen to any single Sirius station for more than a few hours, you will begin to hear some of the same songs. Not so with XM. So I listen to XM much more than I do Sirius.

I also still have the problem of receiving Sirius signals in my car when there are ANY trees or other obstructions. XM drops out occasionally, but it's bearable. My partner and I did a test and found that the number of Sirius drop outs in a given stretch of wooded highway (about 8 miles) were 2-3 times more than XM's. I used to work for the company that built Sirius's satellites, so I did some research and discovered what may be the main reason for this. Their 3 satellite, middle earth-orbit, "figure-8" configuration was designed to transmit at a lower angle, supposedly allowing them to transmit under obstructions such as tree branches better than the 2 much higher angle XM geo-synchronous orbit satellites. But they also didn't build as many ground repeater stations as a result. It's the number and proximity of the ground repeaters that gives us better XM coverage, at least in our area along the Calif coastal mountains.

We have also had a problem with our mobile Audiovox receiver. Again with a lot more research, I discovered that these units tend to get very hot (you can almost burn yourself on ours after being on for a couple of hours). When ours and others I've read about reach a certain temp, they tend to start dropping out frequently. I bought a small clip-on fan for $10 at a hardware store and have solved at least about half of the problem. We still get drop-outs but only about half as many, and the unit doesn't get hot any more. I read that the reason for the excessive heat is that Sirius started from scratch on their receivers, making the chips first generation and therefore requiring a larger, hotter chip to operate. The same discussion said that XM started with existing technology, so their mobile units are smaller 2nd generation and therefore don't generate as much heat. Aside from this problem, I still like the sound and features of the Sirius Audiovox unit more than the XM Delphi SkyFi unit.

Now I'm waiting for the full line-up of second generation of Sirius and XM technology to come out. It started a couple months ago and is continuing up through the holidays. I'm hoping that upgrades to both mobile receivers will help with some of the drawbacks of each. Plus I'm looking forward to some of the higher end audio companies getting into the satellite radio market with their equipment. As audio equipment goes, the first generation releases of both companies were about as low-end as you can get. With over 2.5 million subscribers between the two companies, that size market has to be drawing the attention of the higher end audio gear companies.

If only we could marry the best features of both XM and Sirius - music choices, signal quality, and technology ...sigh...

Arian, I think you have the information about the orbit paths of Sirius and XM satellites reversed. The satellites that Sirius operates actually orbit at a higher angle than those of XM. XM's two birds are indeed in a geosynchronous orbit, but they are positioned directly over the equator like most communications satellites. Therefore, the best signal from the U.S. is obtained by aiming the antenna to the south at a low angle. XM has built more repeaters in urban areas; their signal tends to fade around tall buildings and other obstructions because their satellites are located so low on the horizon. On the other hand, Sirius has three satellites that maintain elliptical orbits (not centered on the equator). They are generally moving from north to south but achieve their highest angles over the upper Midwest. That means the company recommends aiming antennas toward South Dakota, Nebraska, and Iowa to get the best signal. Based on this information, Sirius would be the better choice for people living in areas with obstructions because its signal can be received by aiming the antenna higher. A user needs a clear view of the southern sky to optimize reception of XM; therefore, a person living out on the plains in a rural community would be more likely to receive a clear signal from XM's satellites than a person in a city like New York or Boston.

Um, you were right the first time when you said Clear Channel was ultra-conservative:
Read all about it by clinking on this sentence.

I just got Sirius and I wished that I went to this board before activating the system. I would have traded the gift in for XM. It's great in the car, but buying the boombox is a true waste of money. I cannot get a signal for anything. I am so angry!!

"On both my home and car systems, I have to turn up the volume 4-5 db when I switch from Sirius to XM. I'm no sound engineer, but I do know that the signal to noise ratio affects signal quality, so that alone gives Sirius the edge in signal quality."

This has more to do with the analog audio output coming from your XM and Sirius radios, and nothing to do with the signal quality, which is digital. If they used analog reception, you might (but wound not necessairly) be right.

I found that the sound quality on Sirius varies from channel to channel. The quality of the NPR (talk) channels, for instance, is significanly lower compared to that received through FM. At times, it's hard to understand what is being said. No problem when listening to the same program on FM. I am also disappointed that certain NPR programs (like Morning Edition) are not broadcast on Sirius. Probably some kind of deal to protect the local NPR stations.

I have three accounts with SIRIUS. I am extremely disappointed with them for removing the FOX NEWS from their line up. Listening to the news now has a left wing tilt to it with CNN being the their big news player.

Why can't they have both like XM?

If sirius only had Howard Stern to offer to its listeners, it would still be worth every penny and then some. I honestly have never heard XM radio but im very much pleased with Sirius so why fix something thats not broken.