I have had a D70 MK2 with an Sp9 MK1 since 1988 with no problems.I bought the SP9 new when it came out ($1700 in 1988)and the D70 ($1000 1990 floor model )from a dealer with used tubes. I ordered ARC tubes and used them for a long time. The ARC tubes are better. Back then it was about $200 for a set. I have had the set for 20 years with Vandersteen 2Cs. Tired of the audio bug and just listened to music.
Thoughts on Audio Research D70
I recently saw a very well priced D70. If I remember back in 80's these were highly thought of. Having no chance to hear, what do they compare with today or do they?