After finishing my 2 Pis I hooked it up to my Marantz 2252 and did a A/B comparison with my other high priced speakers and the 2 Pi became my Stereo speaker of choice

However, after sometime listening to the 2Pis I thought the bass could be better, so after re-arranging internal speaker insulation I settled on an improved midrange sound but still no major improvement in the bass department.

Around Christmans time frame, a friend of my gave me two home brew Dynaco Mark III mono blocks that was reglected for sometime... not knowing much about tubes, I paid a tech to get it fixed... afterwards I hooked it up to my 2 Pis and BINGO, the sound was amazing, smooth and relaxed... later on I started to do further research into Mark III design and reliased that the original builder of the Mark III had some fundamental questionable circuits in the unit, long story short I ended up rebuilding my Mark IIIs according to the original spec using new capacitors, etc also became more knowledgeable about tube circuits.
My new setup involves Marantz 2252 acting as my pre-amp, 2 updated Danyco Mark IIIs, and 2 Pi towers. The sound coming out of the 2 Pis is now incredibly smooth, the bass is there now (which could be better when it was connected to the Marantz) and I can truely claim there is no listening fatigue whatsoever and I can listen to the 2 Pis all day long.... Perhaps the sound of tube amps is what you are after and if you are electronics savy there are plenty of tube amp kits/projects out there. Or you may consider rebuilding and old Dynaco amp?