I'll jump in here and give some feedback on my experiences.

I purchased a 990 and 755. I've been very happy with my purchase, the sound for movies has been excellent and I've been quite happy with the music side also (with one caveat that I'll get to in a minute). I truly believe I'm getting the most for my dollar for the products I purchased.

I have the Home Theater Master MX-500 which I've been very happy with. It eliminated all remotes down to this one but now I have to take the time to "teach" it the 990's moves since there doesn't appear to be a way to upgrade the MX-500 with a 990 code.

There is one aspect of the 990 that has been a real pain in the butt (to me) and that's having to connect the 990 to the TV to make configuration changes. I had my DVD player connected directly to the TV before and had no need to run the connection through my previous receiver. It just seems wrong that you have to buy another cable to enable configuration changes. Others have mentioned this and I guess I shouldn't be so cheap but it seems like I shouldn't have to involve another piece of equipment between the DVD and TV if my setup doesn't require it. I was really cursing the 990 when I was trying to get the lip sync just right. I must have swapped that cable from DVD to 990 a dozen times or more.

Anyway, the one aspect that is quite different from my old receiver is that bass is over-emphasized on some of the music I like to listen to which probably falls under the category of classic rock. You know, Steely Dan, Led Zep, Eagles, Yes, along with Dave Matthews and other similar groups and sounds. I don't know how to describe it exactly other than it's a bass sound that sometimes slightly drowns out the other instruments and vocals. Kind of boomy, you know, when a bass instrument is being played? I never noticed it before with my Yamaha receiver. It's probably more a characteristic of the 755 amp (lots more power) or maybe it's the 990/755 exposing bad recordings. This is something I only notice with music, not movies. Although I'm not sure it's fair to compare the two. I mean how do you compare a bass guitar with a bomb going off.

If anyone has a suggestion as to how this might be corrected I'm all ears. I've tried adjusting the bass control but didn't like how it affected the overall sound of the system so I kept it flat. Same with treble.

I also tried changing from 'stereo' to 'bypass' to 'upsample' but I can't say that I noticed that much difference between the three.

I have PSB Silveri speakers as my mains and no sub. I believe they're quality speakers and I don't believe they're damaged in any way but I can't take the grill off to inspect visually. They're about 3 - 4 feet from the back wall and sit on carpet. The room is large (22 x 24) with lots of heavy furniture and shelves with books. But the set up is not centered, the speakers are oriented towards one end of the room.

Let me finish by saying that I'm very happy with my purchase and I'll be keeping the 990/755 for a long time and will recommend these products to others. The overall sound is very nice, actually great considering the price, and I've been enjoying them immensely. Everything considered I'm much happier with the 990/755 than I was with the Yamaha. The bass is something I'd like to be able to correct if possible and look forward to any feedback.

You are suffering from room modes brought on by more power. (It woke up your speakers) AMPs by themselves don't sound boomy generally.

There is lots you can do from moving the speakers to different locations to restuffing them with more packing, changing the crossover, or purchasing a Behringer 1124 feedback destroyer.

But I start off by moving speakers a bit.

Most of the time reciever don't have the reserve power and the bass is the first thing that suffers. That's why you probably didn't notice it with the Yammy

I have PSB Silver i's on my 990 as well. The grills should come off (mine do), but it might require a little more force than you're expecting. I doubt they're damaged.

Your new amp is probably better capable of driving the PSBs than your old one. The Silver i's have very good bass extension for a modestly sized tower speaker. I ran without a sub for a few years with them and was not disappointed.

The thought that your room is a big contributor here is probably spot on. It might be time to start getting scientific about it.

Get a Radio Shack SPL meter and download and burn this test CD (http://www.realtraps.com/test-cd.htm). Follow the instructions on the site for doing a simple room analysis. This should give you some insight as to how your room is behaving in the low frequency spectrum.

Thanks Trikos and Prefect, I appreciate the feedback.

I'll experiment more with location and download the test CD. I'll follow-up with the results.

Thanks again.

Mark