Not to many people with knowledge or interest in Rogue I see! Too bad for them.I cant help you out with the M-120's but I have a Rogue 99 preamp that has 2 12ax7's and 2 12au7's in the phonostage.I replaced the supplied tubes with 12ax7 Telefunkens and the 12au7's with Radiotecniques.HUGE,HUGE improvement!! Call Kevin Deal @ upscale audio.Get good NOS they are worth it.Maybe also Mark can steer you in the right direction also.If you call Mark tell him Dave said HI!