My bedroom system consists of an old Yamaha integrated, a cheapo DVD player for CD playback, and and old set of Cambridge Soundworks Ensemble II speakers. A few weeks ago the Yamaha started acting up. Rather than get it repaired, I purchased one of the Sonic Impact T-Amps that have been causing such a stir. It cost me around $40 shipped new in the box off of Ebay.
I got it about a week ago. I hooked it up in my bedroom, powering it with 8 AA batteries and using cheapo Radio Shack interconnects and speaker wires. My first impression was good....it will definitely suffice for a low-volume bedroom system. However, the speakers aren't very efficient, and aren't that good, so I thought I would give it a spin in my main system. My main system is *not* very high end, but is certainly better than the junk in the bedroom:
NAD C320BEE integrated amp
NAD 521i CD player
Ascend Acoustics CBM-170 speakers (which are pretty efficient)
Heavy-gauge speaker cable that Ascend Acoustics sells
(plus a turntable & preamp, and a powered subwoofer, but they were not used for the comparison)
So, I played a couple tracks off of Michael Houser's Sandbox CD with the T-Amp powering things. My first impression was "wow!". This little battery-operated toy filled up my living room with music! I could hear subtle details and the imaging and soundstage were impressive. It seemed very clean and forward sounding. Maybe a little lean in the bass.
I switched to the NAD C320BEE powering things, and the bass definitely beefed up. The overall sound was more "polite" and laid back....still plenty of detail, but not as in-your-face. I noticed that one particular guitar part that really soars (on "Low Country") had more of an emotional impact.
I switched back to the T-Amp and this confirmed my impressions. Some of the bass issue could, I guess, be attributed to the battery power and cheap speaker cable (no way to use the heavy cable with a stock T-Amp), plus the fact that it had maybe one hour of break-in. But here's the amazing thing: this little $40 amp held it's own with an amp costing 10 times as much! As I told my wife, if I had plugged in the NAD 3 years ago when I got it, and it had sounded like the T-Amp, I would not have been dissatisfied.
Pretty amazing.