I remember those times very well Dave. You sold me my first SP8 and I repaired a lot of ARC products for you over the years. It was the SP10 that had all the valves and was the troublesome preamp. There were 8 valves (6DJ8/ECC88) all double triodes in the phono stage and 4 valves (6DJ8/ECC88) all double triodes in the line stage, so 12 in total, plus another 3 valves in the power supply case. The problem was keeping a noise free set of valves in the amplifier which was very difficult to achieve due to the large number of valves used in the design, plus the very high gain of the whole preamp. Any noise was massively amplified by the high gain. The SP11 was ARCs answer to the very noisy SP10 and was rapidly rushed out to prevent the slide of the company due to these products downward reputation. The SP11 has 2 token valves/tubes in circuit, one in the phono stage and one in the line stage. The main gain circuits were all solid state to keep the noise levels low and try to recover some credibility for the company. Sound wise the SP11 was nowhere near as good as the SP8 and SP10. Same for the SP9 vs the SP8 as that had a similar design in the it was more solid state than valve. You might as well have bought a Krell or Mark Levinson as opposed an SP11 as the SP11 sounded just like a solid state amplifier and not tube like at all. Do you remember the SP12 Dave? I remember you had one in the shop in Radlett. That was a cracking single box preamp too, much like the SP6, SP8 and very underrated.
Do you remember that customer from Berkhampstead Dave, who came in your shop one Saturday with his SP8 and D115? I was helping you that day. He had just bought both from Popeck at Subjective Audio? The customer was worried about buying a valve amplifier due to some not being as reliable as solid state. But Popeck had sold him the SP8/D115 telling him that he would always be there for support so he needn't worry. Two weeks later when the power amp blew up he took it back to Subjective Audio and the shop had gone! He came to you in desperation thinking he had just been sold a pup. We repaired it for him. It was another ARC amp that had never been biassed up correctly by the dealer that sold it (Subjective Audio).
As you say the Croft and EAR amps had much better reliability. Happy days...