Hi, I have the XRS / Trends T-amp. I should be getting a new (used) tube preamp for the system tomorrow. I think it will get me that extra texture, presence and body that the Trends is a bit short on. I was considering a tube amp, and might go that way eventually, but for now I'm running the amp off of a battery with a capacitor bank, and I bought new input caps, resistors and power supply caps to add to it. If you have an SI amp theres a lot of surface mount components, not as easy to modify...
As far as amps, maybe the Vista i84? I haven't heard it, but it looks like a contender.
Also, ICs and speaker cables have made substantial differences in the sound.
Dave