Music Reference RM9 - user comments please


I am considering of getting a used RM9 for my Merlin-TSM, can any user of the amp comments.
vintage
I own a RM9 MK1 with KT88 tubes.
I think it is a wonderful amp.
Can anyone tell me how much needs to spent $$$$ to better this amp significantly.
Thanks
I think you are already at the forefront of what you should expect from a great tube amp at that power rating - changing to EL34s will give you another sonic signature though.