We ran his PH-16 into one of the line level inputs on my preamp, which seemed like the logical way to compare. There was a lot of powering on/off and moving plugs for this, but it all turned out worthwhile.
The two recordings we listened to most were Scott Hamilton playing "That's All " and Wesla Whitfield "I'm So Lucky To Be Me ". These links are to digital versions ripped from CD. Full Redbook resolution.
There was a considerable difference between the PH-12 and PH-16. Keep in mind that I've been listening to the PH-12 for about 6 years now, so I am very used to hearing that sound, and thus see that as how it is supposed to sound. The PH-16 was much darker, richer and almost "woolly" in the way it sounded. Particularly in the mid-range.
Then my buddy asked me what tubes I had in there and I had no idea. So we opened it up and found JJ EC88 tubes, which are a respected and low cost Chinese tube. He then pulled out his box-o-extra-tubes and we did some tube rolling. Wow. What a surprise! We listened to both Electro Harmonix and Phillips 6922 tubes. Both were less bright than the JJ EC88. The Phillips had the PH-12 sounding almost like the PH-16! Very interesting.
What kinds of EC88/6922 tube rolling have y'all done and what to you recommend?
And in case anyone is wondering what I'm running for tubes in the SP-13 line stage, I have Brimar Mazda 6CG7 tubes for the front end and the originally supplied RCA Clear Top 6CG7 in the back end.