A few weeks ago @Jh4db536 came over to my place to compare his Fostex T900 super tweeters against my friends T500mkII that are on loan in my system. I was surprised that he brought over his DIY modded DG300b speaker amp, and I'm glad I had the chance to listen to it in my system. It is a beast that he put his personal touches on, and his attention to detail and practicality was awesome. In my 2 channel system, it made the AF sound slow and bloomy, and I was a little disappointed, but we discussed what changes he did to his amp and how he tuned the sound to his liking. It boiled down to modern Russian 300b tubes, and replacing the original caps with the very reasonably priced Jantzen Superior and maybe another secret sauce mod or two. I really like the sound of his 300b amp, fast clean and dynamic, although the AF was at a slight disadvantage power wise, approximately 4W vs 8W. The 300b amp bridged the gap between the AF and the Pioneer M-22 I also had to compare, with the 300b leaning more towards the solid state M-22. I set out to head down the righteous path of less bloom... First the Russian EH 2A3 tubes were found for a song on ebay lightly used and tested to spec when they arrived. Jantzen Superior caps were ordered, and the wheels were put in motion. I tracked down a thread here that refereed to the caps tested in the development of the AF. I went with the number 2 pick the Jantzen's and not Jupiter, partly due to price (1/4 of the price) and a few people have had long term reliability problems with them in other applications even though they start out crazy good, but have had a tendency to deteriorate quick. I didn't feel like rolling the dice... http://www.superbestaudiofriends.org/index.php?threads/capacitors.4106/ I unplugged the AF from power overnight, and tore into it this evening. The stock Russian caps (with a great reputation for value) were pulled and the Jantzen's went in. Doing this on your own WILL VOID YOUR WARRANTY, not to mention the usual dangers of high voltage and death, etc. First of all, for those that don't know me, I'm a HD600 guy, not an HD650 guy. I did this mod for my speakers not my headphones (which I enjoyed with the Russian caps), but felt a little too much bloom with my Fostex speakers. 2 albums in this evening, and the fat I was looking to trim is gone... This mod will not be for everyone, but it works very well in my set up. It also helps to have the the devastatingly good T500mkII tweeters, they did noticeably best their little brother, the T900's when we compared them head to head. I tortured @Jh4db536 with a few tracks of MJ's "Thriller" album (80's CD), and the difference became more apparent than with a few other genre's and tracks.