Steve I just read your review, so thorough and inciteful. I hope you do a video on the SLP-05.
Loving mine for over a year with a Pass XA-25 and Harbeth SHL5+ speakers.
One thing, the ’05 does have gain control. The two knobs on the right for left / right continuously variable adjustment. It was fairly easy to dial in the best sounding gain including a slight trim to adjust for a minor channel imbalance in my room.
Bingo on the Mullard rectifer, big difference. If you get a chance try a combo of KEN-RAD VT231 in the first 4 positions and a pair of Sylvania 6SN7 GTA 50’s date codes in the two balanced connection tube positions 3 and 6.
A nice balance between old school liquid richness (KR’s) and modern day detail and dynamics (Sylv’s).
BTW definitely continue to use balanced connections for sources and amplifier, the balanced circuitry runs through another set of tubes vs. single ended and the sound stage is more open and spacious in all directions.
Mine is sans the ultimate upgrades and I love the sound so much I am afraid to risk it changing- at all !
peace, Tony