Opinions on Audio Research SP5

Anyone have any experience with an Audio Reserach SP5 Preamp. I know that it is a solid state design. how does it compare to other ARC preamp units?
Pretty old now, isn't it? May need to be rebuilt. I had an SP-6 that was modified to remove protection circuitry. It was a tube pre-amp, which I used with a SS amp. Incredible.
The Audio mags of the time were not all that impressed i.e. absolute sound, etc. The ARC tube gear totally outclassed the early ARC solid state.
Had an SP5 at the time it first came out.......hated it....do not buy!!!