Summary:
Here are the specific reasons why I dislike this product:
1 - 30 day acoustic superiority warranty. Expect to pay hell if you try to exercise it.
2 - Parts are not sent which are used, and vice versa. Rather confusing. Wrong parts sent, like big ones, like transformers. Several calls.
3 - Vague instructions, like you clip a resistor lead which they want you to solder something to later (#^^&$@!!!)
4- Last minute changes, but board is not modified to solder to. Not even marked.
5 - Get this...the solder pads which take the upgraded components are already filled with solder,(silver hi temp) It would be better to let the buyer build the entire board, his choice of components, cheaper too. Cooks the expensive $5 chaddok resistors
6 - Wrong quantity of components marked vs. sent.
7 - Op amps packaging - er, there is NONE !! WHAT? RIGHT!! Just thrown in a bag. Leads get bent up all over the place, almost break off. They ship the $16 (!!) AD827's like this too! Unbelievable!!
8 - Wrong version of manual sent.
Summary - This kit is not that complicated to merit the above oversights. Do not attempt this if you are hypertensive, have heart disease, or suffer from a mood disorder. This kit reaffirms the basic tweeker's anxiety, that "kit building CAN be bad".

Strengths:
Every input imaginable

Weaknesses:
So what, it doesn't work

Similar Products Used:
Many

Summary:
I ordered this with all the options, every upgradable component, and the 24 bit daughterboard. This is a kit. I added even more options than usually available. It did not come with the Vishay resistors, as advertised. I do not think that would have made any difference. I assembled the kit with great precision and under magnification. This is not a difficult kit, but for 8 major reasons, the manufacturer made this an extremely difficult build. Their estimated 3 hour assembly wound up as 10 x 8 hour days. I tested this at home, and at two audio salons. I tested it with Stereophile CD's, my DAT, etc., and A-B'd the toslink, RCA, and Balanced inputs and both outputs - RCA and Balanced. I did not test the ST or the I2S input. I also verified my results with a 'scope and other audiophiles. I tested it against inboard and outboard DACs, expensive and cheap. The result? No difference. Nothing at all. I called Sonic Frontiers / The Parts Connection, I called their competitors. Nobody could believe this. Audiophiles at the three locations couldn't understand it. I wonder how many people correctly A-B equipment now. This is a well engineered product, but it does not improve anything. That fact, with the avoidable difficulties of kit implementation, rates itself a "0", however the minimum rating is a default "1" of "5", "1" being lowest.