Jam840, you will have a tough time improving on the SP8II. You will certainly have to spend big bucks. The SP8 is a really good preamp which is very tough to beat at any price. The SP6 is also good but not in the league of the 8. The 8 has a great midrange and is just musical and involving.
upgrade ARC SP-8
I am running ARC Classic 60's amp, new caps tubes and resister upgrade; with ARC SP-8II pre; Martin Logan CLS-1's; and ML Depth sub. I am looking to upgrade the pre. I am worried about mixing newer tech with an older system, If I spend the bucks will I do not get the bang. Any suggestions on what to look at?