Where for a tube-newb to start?

Thanks for all the replies!

@Zd542: I am not looking for an amp review. I have inherited the amp from my brother-in-law (RIP). I do not know what tubes may be in the amp at this point. He and I had similar musical preferences, and a tendency to tinker, so I suspect that 1) the tubes that are in the amp are not stock, and 2) I will like what’s in it when it arrives. At the very least, I will have to replace tubes as they go bad and was looking for advice on high-quality replacements, reliable tube vendors, and good sources of background information and in-depth tube comparisons.

@Rodman99999: Thanks for the links!

@Whart: I tend not to seek out the anecdotal, “you really need to listen to ______” (fill in any particular component), reviews. I’d be more interested in thorough, systematic reviews of a variety of tubes with ratings in a variety of categories. I don’t have sufficient background to know what those categories might be. I’m on a relatively steep learning curve at the moment.

@Wolf_garcia: Great link! I wish they had my M520 in the “Shop by Amp” section.

@Buconero117: LOL… Hi, my name is Brian and I’m an audio-holic.

@Bajaed: You said it much more succinctly than I did above.

Cheers... Brian

@Whart: Thanks for all the information! I have received the unit and found that it was populated with that appear to be stock tubes. Frankly, they sound awesome with my Spendor SP1/2e speakers (also inherited with the M520). I’ll be quite happy listening to them while I find “rolling” alternatives.

@Tbg: The amp has Eastern Electronic “Performance Grade” tubes (5 per channel: EF86; 12AU7; EL34 [x2]; 5AR4). I’ll be checking audioasylum as you suggest.

@Zd542: Thanks for the link to The Cable Co. They do appear to have some reasonably priced replacements (e.g. Mullard EL34’s for $37.12 each).

@Brownsfan: Thanks for the recommendations.

@Grimace: I’ll definitely have a look at the resources you site.

Cheers… Brian