Last weekend I did some of the mods described about half way down the page here on the MP301: http://www.canuckaudiomart.com/forum/viewtopic.php?f=23&t=45210 I replaced the main filter caps which were 180uF 450v with larger 390uF caps, and the large cap on the underside of the board with one of the removed 180uF caps. Then I clipped the driver tube cathode bypass caps as recommended above. My amp had no ground issues and used a different connection method than the example on CAM, so I skipped that. Subjective impressions after a few days break in are: Less euphony, more neutral sound - guessing this is due to cathode bypass cap removal, thus no longer overdriving the tubes, fewer added harmonics. Less headphone hum, quieter speaker background - It's an impedance missmatch with my Senn 558's causing the hum, but it's reduced anyway to nearly nothing. The musical background through speakers seemed quiet before, but now seems perfectly so. Better dynamics - slight increase in bass slam, and slight increase in micro/macro dynamics Here's some pics of the process: This is the view with the bottom of the case removed. The caps highlighted in green are the cathode bypass, easy to clip with a pair of small wire clippers/sturdy nail scissors. The cap boxed in with pink is the one that will be replaced with one of the main filter caps being removed. The red circles show where to desolder one of the main filter caps on the top side of the board, these were hot glued down on the top side and needed to be wiggled vigorously while flowing the solder connection shown here. I used desoldering wick to remove the excess after the main caps were out. The pink arrow shows the 150uF cap which got replaced with one of the 180uF main caps. I desoldered the connection shown by the blue arrow so that the board it's connected to and the associated tangle of wires could be pulled back for better access to the board underneath. The green arrow shows one of the cathode bypass caps that got clipped. Finally, the red box highlights the main filter caps on the top of the board, I checked these and the other large cap with a DMM and discharged with a 47k resistor before touching anything for safety. The pink box shows the solder connection for the 150uF cap on the other side. This is all basically the same info as on CAM, but with a slightly different version of the amp and a little more step by step of how it's done. I'm noob at electronics, but a little reading and picture taking got it done, put back together, and sounding nice. Hope the post helps somebody.