I still use my 17 year old BAT VK-60 with original tubes to power my Von Schweikert VR-5 Anniversary speakers. I recently changed the four Jensen caps inside the VK-60 to Dueland CAST copper and am astounded by the improvement in sound stage, frequency range, clarity and realism. The VK-60 after the cap change sounds better to me than any other amp I've heard, even better than the amp that Von Schweikert had on my speaker pair at his shop in Riverside, CA. The four caps cost nearly $800 (I installed them myself), but they're a bargain compared to the cost of buying a new amplifier, even if I could find one I like. I don't know if the VK-55 or 55SE would benefit from Dueland caps, but I sure am happy with what they did for my VK-60.