Defective KR Audio T-1610 tubes

One week ago I received my used pair of KR Audio DXL monoblocks. They sound AMAZING, really in another level than my prior Rogue Apollo amps.
After a week or so, I’ve noticed that two tubes light only in halves. This tubes has two parts, upper and lower.
I have an spare one, but same thing.
The sound is ok, didn’t notice a differnce, at least at my usual listening volume levels.
I’ve already contacted Eunice Kron and Marek, and they confirmed that I have to replace the tubes. The price of this tubes is €2100 plus shipping per matched pair, direct from the factory in Czech Republic.
Still couldn’t find a dealer in the US that can give a quote for a pair...
Any suggestion?