Music Reference RM9 - user comments please

I'll say one thing, I've never heard a bad word said about a MR amp by anyone who has owned one.

Nice to see a current thread about this amp. I've owned the RM9 for just a few months, after buying it from the 2nd owner here on A'gon. I'm only a couple of years in the hobby, so no expert my any means; but no complaints about this amp. Love the looks of it in the dark (never put the cage on after I got it - looks like a cityscape at night) It came with RAM labs 6550's in it and am wondering what I might expect if I changed to KT 88's. Anyone care to give an opinion?
CD source is a Shanling T80 with RCA black gates, fed directly into the amp, through some TaraLab cables to Quad 22L2 speakers.
Has anyone experimented with different driver tubes?
Thanks in advance for any input.

I changed the driver tubes to 6n23p and I love them.Troy

I have sold my RM10 and a RM9 MKII is on the way. I am very interested to see how it compares with my CAT JL2 - it owuld be nice to go from 16 output tube to 8; if the sound is of comparable performance.

The two front driver tubes will have a audible effect on sound quality. I've settled on NOS Amperex orange globe (Holland) a-frame 6dj8. Very smooth but still detailed.