What improvements would I get with a "better" preamp?


Current preamp is Mapletree Audio 2A/SE Linestage, upgraded with Black Gate caps. Tube rectified separate power supply. 6SN7 per channel. Point-to-point wired. What could be better (for less than $5,000) and why? Must have RCA ins/outs, not XLR.

rockadanny

billpete, “blind” tube rolling could be really confusing, if no specific design fundamentals’ checked (manufacturer’s voltage map). even excellent tubes can sound bad in design, which was optimized for specific tubes (load line centering, loading, biases). 

@westcoastaudiophile Not sure what you mean by "blind". If the tubes are the same nomenclature as what your preamp was designed for, what is "blind" about making some of your own comparisons?

@billpete “blind” means rolling tubes w/o understanding tube amp design fundamentals, "same nomenclature” tubes over decades have large distribution of key tube performance metrics, that’s why! designer uses tubes available in volumes, at the time of design, to guarantee performance, thus extra step such as verifying voltage map is necessarily. 

@billpete you can do whatever you want / pleased to.. being analog design expert, I am trying to warn, as tube rolling SQ effects could be interpreted wrongly. 

below is an example of load-line of tube in circuit. small changes in tube behavior btw. different manufacturers will cause significant performance impact of the amp.