Musical Concepts Modifications

Hello everyone. I posted a couple of weeks ago regarding upgrading an Adcom GFA 5802 amp. Amongst the fine suggestions I recieved was one from JB recommending that I explore the modification option. Since I am 92% happy with my systems' sound and don't want to go through the whole rebuilding phase again, I thought this made sense. I'm really just looking for a little more high-end extension/resolutuion and a little more transparency wouldn't hurt. I contacted John Hillig @ Musical Concepts and he thinks his Lx Sig Mod would do the trick. I'm just a little nervous about investing in something w/out hearing it first. Ironically, I listen to mostly prog rock and am also worried that the sound may be TOO refined for my taste. I'm wondering if any of you have gone this route, specifically with the 5802? Any info you can provide is greatly appreciated. Thanks, Matt......
Had a 5802 modified by John--was one of the best sounding amps I had ever owned. I moved and sold off all my gear, and am now rebuilding. I am seriously looking at having him mod a 5802 again for me--that or a Pass X-250.
I had a pair of B&K M-200's modded by John, he's great with amps, no regrets at all.
They sound as good as it gets, warm, liquid, detailed and natural.
I've had several amps and preamps, (Hafler, Adcom, B&K) modded by John over the years. He and his work are WONDERFUL! Well worth the cost...
I have over the years owned numerous Musical Concepts and Musical Design products. I am more than satisfied with their components. I currently have an Adcom 5500 modded by John, a Musical Design D-150B amp, a D-140i amp, and (3) Musical Design CD players. They also are very good with any problems that arise. But what I like most about Musical Design is that you can always upgrade as finances allow. I am currently boxing up two of the CD players for updates. I would send all three but, I need something to listen to until the modifications are done. Jim
John's a great guy with a fine ear! I've known him and his mods for twenty years or more and he has always produced first rate product and he stands behind them 100%. You can't go wrong with John's mods. If you ever get a chance stop by and see his place, the sound is awesome and John's quite a character.
Just another endorsement. His cables aren't bad either.
Thank you all for responding. It is sincerely appreciated. I'm going to go for it. The only question is; when can I live without my amp for a few week?!
"Just another endorsement. His cables aren't bad either."

Great interconnects for the money. I remember the first time I used a pair that John sent me: all of a sudden, on a CD that I had listened to many times before in a headphone system, I could hear the guitarist shifting the instrument around as he played, subtle tones and harmonics I had never heard before with the highly reviewed interconnects I had been using.
I too have known John for over twenty years. I have done musical concept mods
and they were always worth the effort. I own his Musical Design products
and they are fantastic for the money. He uses parts that are better than any of the big boys. YOU can't go wrong with John.
Hi everyone. I just wanted to follow up and let you know how I made out with my modification. Well in short I could not be happier. The highend extension and transparency I was seeking have far exceeded my expectations. Sound stage? There is no longer a defined sounstage. My whole downstairs is the soundstage! All the things I liked about the GFA-5802 were maintained and all the annoying weaknesses are now gone. Oh, and no more Adcom "house" sound. The only negative I would mention is that it took over two months for the mods to break in. John said it has to do with the the black gates?. I started to get nervous after awhile as the sound kept fluctuating. But once it settled in, it was perfect. Now I can't help but wonder what he could do with my JVC DVD player. If anyone has anything they would like to share in this regard, it would be appreciated. Thank all of you for recommending John. I do not think I could have possibly done better for the money. Matt........
That's great news, glad you're happy.
I'm calling John and ask if he has any follow-up mods for my M-200's.
(They still sound fabulous after the mods of three years ago, just curious what he might have developed since hehehe)

Thank you for taking the time to post your follow-up story. I've never--ever--heard or read anything bad about John Hillig's mods at all. AND, he tells me that he owns Intuitive Design Summits!
I'll bet those M-200's sound unbelievable. A dealer by me uses a pair of them to audition speakers and the only reason I didn't buy a pair is that they sounded so similar to the 5802. With John's mods, I can only imagine. By the way, this modified 5802 now sounds better than the BAT monos I auditioned. Way more lower end slam. Thanks again for the recommendation. Matt.......

My M-200's sound absolutely KILLER.
That's why they remain here since I bought them new.
After John's mods were performed, anything in front or behind these amps is revealed.
Other amps I'm considering (if my B&K's ever quit) are a pair of
Channel Island D-200's.
I have also known John Hillig for over 25 years. John highly modified my Hafler DH200 and completely rebuilt my Hafler DH101 with his own board back in 1977. I don't think he had his Musical Designs yet at that time. He has come a long way. Yes, John uses the best parts available. I don't see his ads much anymore or even read his threads here on Audiogon. I guess he's a busy man. I enjoyed his modded products, but sold them all back early in my marriage when the family took priority over my hobby. I actually took a 15 year hiatus from being an audiophile. I took it up again 3 years ago after the kids left home to start their own families. I am more involved in audio now than ever before. Enjoy your newly modded products and enjoy the music.
John is building a brand new D-75B Signature for me as we speak. Can't wait..
what is johns full email address and do you know rather his doing mods anymore want to have my b&k 200s done.or phone #
thanks chip
Here you go.
Google Musical Concepts for info. The email for John appears to be::