What was its main function for you? PA system? Hi-Fi amp? Just checked out the link and the main circuit diagram. Cool that people are keeping it going after 40 years.
As a 10 YO, I had a Fisher model 50-A tube amp with a heathkit pre-amp. It sounded nice until i drilled a hole through the winding of the intersrage transformer, so I scrapped it. I learned some tube repair skills. It is a sought after tuner, even now. ebay had one for about $700 USD recently. A modified cloone goes for about $10.000 each new. So, I guess I knew what quality sound was. We used to have tube radios around the house. They need some serious work.
When I was putting audio together, I could not afford much, My parent bought an AM/FM Electrophonic Stereo with detachable speakers and a turntable with a ceramic cartridge. Grand total, maybe $150.00. It didn't sound good and had poor FM reception. New, won speakers made the amp sound worse.
I don;t remember the order, but I found a nice power/preamp at a garage sale and I gut the power amp section and I built an RE amplifier that was supposed to be for car based on the NE-540 chip. I had to wind the transformer for that one.
I took a rather slow upgrade path. The first component was a Technics Sl-1700 direct drive semi-automatic turntable. It ejected and parked the tome-arm at the end of playing. It's like, why buy albums if the player will damage them. Invested in record cleaning kits and finally a moving coil cartridge.
I effectively ended up with 3 pieces from this Technics Professional Series:
https://www.preservationsound.com/?p=6908. The FM tuner which is fantastic, the pre-amp and the EQ. The pre-amp has a frequency response from 0 to 100 kHz. With the tuner and the rotator, I could receive a different station on the same frequency by turning the antenna. At some point I added the kit Radio-Electronics Timer as a sleep timer and I built a 12 band EQ that was in RE for about $100.00. It too had a frequency response out to 100 kHz.
To make the FM sound even better I acquired a 4bx dynamic range expander from dbx. Retail was $1000. It expanded in 3 bands and had impact restoration, so you could adjust and hear keys hitting the strings on a piano. And I acquired the carver TX1-11 FM charged-coupled decoder which was an external signal processor for FM multi-path.
Cassettes were also popular, so I got a Technics RSB-100 with direct drive. With metal tape and dbx compression, it could achieve up to 25-28 kHz response. dbx was superior to Dolby but rare. Longevity and no belts were primary.
Unfortunately, two portable CD players got either stolen or lost. One had optical out and an IR remote. I miss both of them. I was given a CD player whose motor sticks and I found a changer one for free without a remote.
One of those plans that never materialized was to record FM onto super VHS tapes. I bought a JVC HRS-7000U super VHS recorder with a switched outlet
that could record audio only.
Things now just aren't the same anymore.
I acquired the pre-amp new and the EQ used.
https://www.preservationsound.com/?p=6908