I bit the bullet by recently replacing the tubes in my REGA ISIS VALVE cdp/DAC with NOS MULLARDs.
Were they better ? Yes. No surprise here.
Were they worth it ?
(1) That is a personal value judgement, because they are comparatively expensive. (2) In short …. “YES” for me, because it’s for a $13,000+ unit wherein
(a) the added outlay for NOS MULLARDs is a very modest percentage of the sum total , and
(b) the added performance improvement quotient in a highend unit actually capable of the added resolution in NOS MULLARDs is clear and unambiguous.
Would I spend the cash for NOS MULLARDs on a modestly built and modestly priced unit? No…it’s a very risky poker shoot at best for units in this pricepoint strata , and a highly likely disappointing outcome in a common sense approach for failures …for the same reasons highlighted above. They alone won’t be a silver bullet fix providing a Jesus moment here.