audio research

There was much controversy on the SP-9 with conflicting reviews when new. I auditioned one from a dealer and thought it sounded wonderful. The one I bought was sealed in the box and did not sound nearly as good, so I returned it.

I never followed up on differences between different ARC versions but my recommendation would be never buy a SP-9 without a trial audition in your system.

I prefer the SP-8 over the SP-9. The SP-8 can be notably improved by replacing the Rel-Cap coupling capacitors and bypassing the opto-coupler in the mute control.

Audio Research SP-8 MKII is the match for your D-70. There is a big difference between an SP-8 and SP-8 MKII.

I would not go with the SP-9 unless it was a MKIII version. The SP-9 had issues with crosstalk and manifests itself as a lack of space between instruments, as well as a somewhat gray back-ground instead of black. Old f.e.t technology. Instead I would opt for the SP-8, the version with the tube rectifier. That was manufactured around the same time as the D-70 MKII. If you can afford it the SP-10 would be my choice. It is more open, and it offers greater detail. It's phono stage is quite a bit better then the SP-8 providing you can keep it in low noise tubes which now a days is not a problem. If its stock expect to recap the unit. There are a few capacitors in the power supply that need to be replaced. Also, the voltage regulator stages will need to be checked for noise.

Well I am in error. After looking up the circuit diagrams the SP-8 does not have a tube rectifier, it has a tube voltage regulator which I still prefer, easier on the tubes. Sorry for the confusion. This is what happens when you don't check your facts. My bad.