What are your go to LP's for evaluating new gear or new tubes?

I generally avoid "audiophile" records for evaluation and set up.

For arm/cartridge VTA, I use the time proven Dave Shreve favorite, flying fish HDS 701, Sauerkraut and Solar Energy track from this bluegrass album: https://www.discogs.com/release/8082236-Norman-Blake-2-Tut-Taylor-Sam-Bush-Butch-Robins-Vassar-Clements-David-Holland-Jethro-Burns-Norman-Bl

It can sound thin and you’ll know pretty quickly if the high frequencies get dull, there’s an article here about how to do it: https://www.tnt-audio.com/sorgenti/vta_method_e.html

That track is also fun to listen to.

One of my go-to records for getting an overall sense of a system is a bone stock original issue of Janis Ian’s Between the Lines. It has real strings, some tympani, natural sounding vocals and is generally a very well recorded album without sounding "juiced" (Breaking Silence, to me, while a great sounding album with profound bass, can mislead you). I have an "approval" pressing (not exactly a "test pressing" and not a promo of Between the Lines that was released), and the original pressings that were commercially released sound the same as this early pressing.

Although it is good to use records you are familiar with as a reference, I also find that using a wide variety of different material helps to reveal shortcomings.

My general preference is for acoustic instruments, recorded simply, without a lot of multi-tracking or post-production. That may not be what one normally listens to, so I guess using a range of material is useful for that as well.

Yes, first you play piano, vocal and acoustic guitar. If this is not good enough, there is no reason to continue. Then you check for everything else.

billpete,

yes, great recording will sound not too bad on your average $2k system but poor recording will be almost unlistenable.

In my modest system I use MFSL - Supertramp Crime of the Century and Pink Floyd DSOTM, because I like that type of music. I also will use Chris Isaak material because of the way it’s recorded. I particularly like his cover of Orbison’s “ Only the Lonely “. To the OP, I believe your Webcor tubes are relabeled Mullards. Unfortunately I’m not a Mullard guy and to me they sound like someone threw a blanket over my system. I’m a fan of Tekefunkens and within them prefer the G73-R’s and then the Tektronix or other Medical grade. If you’re looking for something that’s totally opposite of your Webcors try the Silver plate Seimens. Also to comment on Al DeMiola, I sat front row at a small theater a few years back and I never was a big fan of progressive rock. However Al played an acoustic set and rotated between conventional and classical guitars and he was phenomenal ! But I lack the depth of intelligence to appreciate music that complex. FWIT he told stories between songs and said his friend Mike gave Chick Correa a demo tape he recorded and that’s what landed him with Chick. But the kicker was when Mike recorded him, he was loaded on Acid. Then he joked that the way to Carnegie Hall was not “ Practice, Practice, Practice “ , it was “ Acid, Acid, Acid”.  Cheers to all and Happy Listening , Mike B. 

Di Meola's album that I mentioned is very very different. It was recorded in 1985, that's when I heard it for the first time. Mesmerizing and unusual non-trivial music. I don't like his fusion style and electric guitar work, with some exceptions. For his acoustic guitar performance try also Heart Of The Immigrants CD. A few compositions are excellent, well recorded for the time as well.

Sea Change by Beck is a beautiful recording.

Masterpieces by Duke Ellington.  The acoustic instruments really shine on tubes.