You could do them yourself if you had a schematic diagram showing you which tubes go where. But the cost would still be between $3,500 - $4,500 for new tubes for both monoblocks. Then biasing the tubes, etc......
I agree with other posters, a brand new Ref75 or Ref150 or used Ref250's would be sonically superior and more reliable (and cheaper in the long run!)
I agree with other posters, a brand new Ref75 or Ref150 or used Ref250's would be sonically superior and more reliable (and cheaper in the long run!)