I’d avoid the Tubes4HiFi/VTA like CoViD-19.
Tubes4HiFi/VTA products are poorly designed to be as cheap as possible.
I bought a factory built pair of the M-125 monoblocks. Factory built, the absolute worst assembly of any tube amp owned in over 50 years. They come nowhere close meeting the claimed specs. see
http://www.ielogical.com/Audio/VTA_M-125.php.
IMO, the designs suffers from fatal flaws [e.g. un-compensated LM334 causes gain to vary slightly between channels over about 10 minutes after an inordinately long warm up] and poor gain structure choices. They are marginally stable. Most will not have issues, but some... see
https://i.postimg.cc/gcKSXW7f/Num1-Unstable.png in
https://dynacotubeaudio.forumotion.com/t4217p50-m-125-build#42336 for an example.
They can be made to work properly for very little extra work.
Smilin’ Big Bob called me an Audio Zealot, banned my DTAF account and deleted my posts. People from all over the world have contacted me with similar issues with both their amplifiers and lack of support from Messrs. Latino & Mottram.
BTW, ignore all tube rolling advice. Just as amplifiers sound different in different systems, so to with tubes. Tubes vary greatly, not only from brand to brand, but
from tube to tube and over time.