Hello,
This is a response to traveling Randy from S. Africa, Be assured the Prima Luna amplifiers are ALL tube designs, with no transisitors or IC's in the signal paths. The active bias circuit uses a series of caps and resistors that biases each output tube individually, controlled by a central IC circuit, monitoring changes with each tube as it ages. There is no direct correlation or affect with its tube sound or its usage with the prescribed tubes as desired. The ultra-linear design has all the tube robust sound as its design was intended. No worry with these products becoming obsolescence or its parts including the IC, becoming none existant. Prima Luna has parts for this lifetime and the next for its products. Please do not conclude a products worth, without trying it out or asking questions from its designer or distributor. There is no excuse for ignorance, ask questions and be informative. The Prima amps are Great! As good as it gets, without the bias conflict worrying about tube aging and the use of unmatched tubes. If a tube goes bad, you replace the tube and a protective fuse, without a service charge. These amplifers mark an advancement of worry free design and enjoyment.
Best Regards,
Robert, An audiophile listener, builder, sales and service for the past 30 years...