VTL 450 Monos and 5.5 Pre. Stock tube manufacturer

Does anyone know who makes the stock tubes for the VTL MB450 Signature Mono Blocks and the 5.5 preamp ? Im lookng to do a complete retube on both.
they use svletana 6550 for the amps , dont know about the 5.5 but just call vtl and talk to bea lam, they will take good care of you tel. 909]627-5944
Make sure to contact VTL or a VTL dealer... I was considering their amps before I purchased the Quicksilver V4's and decided to not consider VTL after the dealer informed me if you use any tube other than what the factory provides it voids the warranty.

To me personally - part of the joy of tube equipment is rolling tubes to get the best synergy...