I posted this question in the turntable forum but didn't receive an answer, so I'm trying here instead. Here goes:
My current system consists of a Forsell Air Reference Turntable/arm, Lyra Parnassus cartridge, an ARC SP-9 Mk 2 preamp, a pair of PrimaLuna Prologue 7 monoblocks, and my most recent acqusition, a pair of MartinLogan Spires. My turntable and cartridge are about 15 years old (although for about 5 of those years they didn't get much use), and my SP-9 was bought used a couple of years ago (I have since had it serviced and retubed by ARC).
To take my system to the next level, I'd like to replace the cartridge with something like the Air Tight PC-1 Supreme, and the SP-9 with the Phono 7 and a Reference 3. The Parnassus sounds fine, but I can't help but wonder how much longer the suspension will last. If/when I buy the Reference 3 or Phono 7 my SP-9 will be performing the duties of the other box. That is, if I get the Phono 7 first I'll use the SP-9 as a line stage, and if I get the Reference 3 first I'll use the SP-9 as a phonostage.
In round numbers each of those components will cost about $10k, and I can't afford to buy more than say one per year. My question is: in which order should I perform these upgrades?