This is my 1st foray into separates - purchased the Modwright LS100 preamp and the KWA100 SE power amp. Rather than install the new issue Sovtek GZ34 & EH 6sn7s that came with the LS100, I went with NOS Sylvania GZ34, and Shuguang Black Treasure CV181-Zs. The amps take 400-600 for full break-in; have about 150 hours thus far and the amps just keep getting more and more musicial - good definition across the frequencies, bass with punch, clarity, nothing veiled. Looking forward to reaching the 400 + hours to hear what they really can do, but very pleased with the decision to get these