HI, I can recommend at least two tube amps, for maybe a couple hundred more than the preamp: The zen amplifier (decware) and the stoetkit amplifier (www.stoetkit.nl). Both have a passive volume cntrol that is very transparent. My guess is you will find far more improvement in sound than with a tube preamp and a ss amp. esp given your pi speaker system (very efficient) and your modded cd player. BTW, i bought a toshiba after seeing the hype, and burned it in and played it. I could not see myself investing time and money in a device that had such low quality parts. SO i returned it. I am curious...how does it sound after the mods? Can you compare it for us to other CD players YOU HAVE HEARD, and maybe post in the digital forum on this website? thanx -akhilesh