Thanks guys. Yes, Ben N. I use grommets to reduce the risk of breaking the tubes and the shock of the tubes. I think that this is typical for device like this where small tubes are used.
EDIT: Also I make a lot of tests with different tubes and my choice was JJ premium gold tubes with long plates. These tubes gives the best sound. The only one disadvantage is the price - 20 euro per tube or 40 euro for tubes inside one unit. The sound is really great. I test this preamp with more than 10 basses - Fender precision, jazzbass, another marcus miller active jazzbass, musicman stingray, 2 warwick basses and a few boutique basses. The sound in all cases was great, but the best what I hear when play was from classic fender precision and jazzbass. Soon I will make some video presentations.