When we started out in 2005, we didn't actively warn any customers about mods and even supported it. Later we discovered that it is difficult to control the quality of the mod and some mods stopped the amp from working and we have to help fix it (free of charge at that time).
So now we stated that we will not authorize, examine or be consulted for any modifications and such modifications will void warranty.
There are more than cost issue with electronic parts. Availability is another issue. For example, we tried another brand of well known audiophile grade capacitor (the cap that we used are also audiophile grade) a few years back and it didn't sound good. We also tried other more expensive op amp and those don't sound good either. Some parts have different performance issue that cause problem too. Anyway, I won't go into specific and as far as we are concerned, the modification case is closed.

Once a design is stable, we don't spend time tweaking it over and over. Therefore there has been not change in V2 amp for more than a year. What we do on R&D is not to tweak existing design (that's not R&D

). We work on the next generation design. It is possible to modify existing design to incrementally improve the sound so I am not saying that all modifications will not work. If you are patient, for the price that you pay for the mod, you could pay for the next generation upgrade, but that could take time. Going from V2 to V3 will take more than 2 years. We don't expect to release V3 until after mid 2009, perhaps even longer.