Tubes Audio Mirror PP1

I just purchased a audio mirror pp1 in fantastic condition, I had one a few years back had to return it as it was slightly damaged but had a chance to listen to it, and now have it back.My components have changed since then and so has the sound.I know there are 7 tubes inside I believe they are stock tubes.Looking for a little more smoother sound(treble) to compliment my coaxial driver.My speakers are 96db and at the moment can't get the volume control past 1/4 turn even with 40 watts per.I have purchased a pair of genelex gold lion ax7 but as I just found out have all the gain I need, I am ok with that if the sound is smoother.Any suggestions would help and where to place the tubes as there is a phono section in the pre, trying to improve the output.
Thank You.