Brian..No mods. None planned. Love the sound just as it is. I run a Melos Phono pre amp into one of the line inputs. If I ever got a sub..I'd run it off the speaker level, so not concerned about a line sub out on mine.
I saw your other thread regarding 6SN7 input tubes. Ive rolled Tung Sol Tall Bottle GTB Black base...To polite for me....RCA 5692 Red Base were very airy and smooth as silk, but bass was way too light....Ken Rad Black Glass had killer bass and mids and wasn't bad on top..I could live with this tube, but I found that the stock Chinese 6N8 is by and away the best so far. It has drive and dynamics and very good bass. Halographic more so than any other Ive tried..so I keep coming back to these. I figure they knew what they were doing when they used this tube. That said, I have a pair of 60's Raytheon Short bottle clear glass on the way to try.
My biggest change came from the 845M's and a pair of 50's Tung Sol 12AX7 that came from a Fender Tweed amp. Really textured and musical. This is my current and best sound so far.
Best,
Ken