I’ve tried about a dozen tubes in my Lyr 3. This includes the factory modern Tung-Sol and a wide variety of vintage tubes (see my old summary description here). I also own Schiit’s LISST, their solid-state tube substitute.
My gut tells me your three options will indeed sound about the same. In my experience changes to the physical construction of the tubes, to include glass tube length, plate differences, and internal build variations, deliver the most obvious sound differences. This gives vintage models uniqueness if not superiority, as I alternatively love, feel “meh,” or truly hate some of my vintage “big name” tubes.
Some examples from memory, and can dig up more notes if you want them:
- The LISST falls in between tubes and the solid state sound – it has the best staging and technicalities of all, but is still laid-back and harmonics-friendly and not unlike my true glass tubes.
- The Schiit bundled Tung-Sol is pretty neutral. It’s okay but kind of boring…perhaps akin to your 3 tubes.
- A vintage Ken-Rad black glass is my most technical true tube. It’s a bit softer and rounder but still pretty technical.
- Vintage Fotons are common, inexpensive, and stereotypically “tubey” – loads of creamy harmonics, thick, and very gentle.
Etc.