The Musical Paradise D2 DAC is a good product! I feel that it has a few shortcomings that we address and that make it truly great!
The mod includes:
Re-bias of the tube stage allowing for lowest distortion and optimum operating point for the tube. We use premium audio-grade resistors in the signal path.
Adjust the operating high voltage supply to the tubes to provide the required optimum voltage for the ideal bias point.
Install MWI bypass capacitors at the B+ supply to the tubes where the stock supply has no bypass caps at all.
Lastly, we install our own proprietary SSHVR - Solid State High Voltage regulator to provide a rigid and solid supply for the critical plate voltage. Without regulation, as the stock design is implemented, any fluctuations in the AC mains supply means some fluctuation in the plate voltage. The best power supply is tightly regulated to allow for robust bass, lower distortion and faster transients. With the SSHVR install, now matter how the AC mains fluctuates and no matter what current demands are required at the tube, the plate voltage remains rock steady.
The end result is better bass, resolution, soundstage, dynamics and speed.
The tube rectifier is still retained and I believe this is important as I like the sound of tube rectification, even WITH Tube Regulation.
To clarify, the tube rectifier converts the AC voltage to DC. The Regulator takes the incoming DC voltage and regulates it to a lower voltage, that is very clean DC and without fluctuation. As the incoming higher voltage to the regulator fluctuates, the regulator maintains the lower voltage at a fixed output. It acts in a way, like a spring, absorbing the incoming voltage fluctuations.
The cost of the modification is $500. This is a fixed price and will not be discounted. Our standard player mods are $2500 for the Oppo, Sony and Marantz players. This mod requires less work of course. You are paying for our knowledge and engineering as well as for the audio grade parts.
Many modification companies exist, and they are largely charging you for the cost of expensive audio grade parts that they simply replace for stock value parts of lower value. I consider this an upgrade but not a modification. A modification involves actually changing and improving the circuit design. A true mod, in my opinion, involves judicious engineering changes that SIGNIFICANTLY improve the product. We also use audio grade parts, where they make the biggest difference. You as customer can easily add damping to the chassis, upgraded footers and other such upgrades. We offer the our knowledge of audio engineering.
I look forward to hearing from you, as I know that there are a lot of Musical Paradise D2 DACs out there and for GOOD REASON! My hat is off to Musical Paradise for their design and what they are able to produce at a VERY low price! The D2 DAC represents an EXCEPTIONAL value in a high end tube DAC!