Thank you both for your input. Actually, my preamp has considerable gain (Jadis JP80, which replaced a Vendetta/Jadis JPL combo years ago), but the Koetsu cartridge I recently purchased is low enough output that it forces me to turn up the volume pots to where tube noise and a persistent hum I still haven't gotten rid of become intrusive (this problem was not noticable with the higher output Ruby 2 cartridge it replaced). I once used an Expressive Technologies step-up with the JP80 for a Transfiguration cartridge with excellent results, but sold that years ago when the Transfig. gave up the ghost. Silly me! I have a chance to pick up a recently manufactured Koetsu step-up for a decent price, with a home trial, and do a favor for a friend at the same time, so ultimately I can decide with my ears, but I was curious about others' experiences because I had not realized Koetsu made them.
