I've replaced the stock rectifier with a NOS Japanese "Mullard" GZ34 copy. That was a most worthwhile upgrade, more dimensionality and better defined bass response. There aren't any alternatives to the 6h30 driver tubes so you either use one of the two current production tubes (which are made in the same factory) or NOS Russian military stock which is expensive and nearly "unobtanium" now. I replaced the stock drivers with NOS 6h30s from the 80s. That result is a more subjective value judgement. When I use the NOS 6h30s in my most high definition system (Tidal Piano Cera speakers and PS Audio M1200 mono amps) the NOS tubes offer improvements; more definition & a less aggressive high frequency response. When I use the LS36.5 with my other system using a DecWare ZenTorii amp and KEF R500 speakers I actually prefer the stock tubes. Also, the use of vibration controlling feet is equally important for maximum performance. I have with good results with Stillpoints SS. ModWright recommends Daedalus isolation feet, which are cheaper than Stillpoints unless you buy the Stillpoints used.
