The first thing I have to say about this great amp is how good it sounds.  It sounds not only live and dynamic, but better than anything else I've heard.  Originally I wanted to bi-amp my JM-Lab speakers using the Granite Audio 860's for the midrange and tweeters, while using my solid state amp for the woofers.  I've heard how great tubes are on the high end and how great SS is on the bottom end.  So, I bought a pair and hooked them up that way.  Yep, it sounded better with the 860's on the top.  Lots better.  Then I tried reversing the amps.  I put the SS on top with the 860's on the woofers.  It still sounded better than all solid state amplification did.  The bass and midbass were much more dynamic and live sounding with the tube amps.  I was surprised.  I didn't expect the 860's to handle the bass so well.  And, I really didn't expect them to outperform my SS amps.

This got me thinking.  So, I hooked up the 860's to drive both the top and bottom.  WOW!  Did that ever sound great!  I put on a CD with a bass fiddle solo.  It sounded so real.  I swear I could actually see strings vibrating.  The audio illusion was that realistic.  Solo singers sounded natural and real just like they were there in front of me.  The sound stage of the voice was big and full and very present.  I admit I was expecting this after reading the press reviews on these amps.  I was expecting them to shine on vocals and they did.  I have a decent size room for my stereo.  I have my JM-Lab speakers set out 5 feet from the back wall.  I didn't use to set them out so far but I wanted to take advantage of the deep soundstage that these 860 amps can project.  I was hearing horns on a jazz CD that sounded like they were 16 to 18 feet behind the speakers.  Listening to these amps with my eyes closed created an illusion that my listening room is much larger than it really is.  (PS.  I am selling the solid state amps and using the money to buy more CDs.)

An amazing part of these amps performance was their ability to articulate the details in the music.  I think this is called micro-dynamics.  The amps were quick enough to articulate these details while letting other ambient and echo sounds drift and decay naturally.  Regardless of the playback  room acoustics, the amps had a live sound to them.  Even studio recordings had an air of life to them.  The recordings I've played had an exciting quality about them.  There was an immediacy to the performances that I've not heard in other amps.  Granite Audio President, Don Hoglund, attributed much of this to the zero feedback design.  He says it lets the circuit do what the music is trying to make it do.  Music starts out live and the zero feedback doesn't put any restrictions on it playing back with it's original life.  Don also said that having monoblocks lets you put the amps closer to the speakers and take advantage of the tremendous listening improvements derived from getting the speaker cables as short as possible.  I don't know if all that is true, but I do know what I heard was awesome,  quick, and extremely accurately detailed.

The amp itself is intriguing.  The simple design and high gloss finish are quite elegant.  The Granite Audio logo barely shows when the amp is in the off position.  It is impressively subtle.  But, when you hit the on button the logo leaps out of the granite in a stunning ruby red glow.  Trust me, it makes a statement.  The back of the enclosure is fully open for cooling the big power tubes.  I've left the amps on for days on end and the top of the granite gets warm but not hot.  Those granite guys know what they're doing with the heat.

Don said the logo and word "POWER" are engraved into the granite and epoxy filled before being polished flush.  He said the enclosure can be buffed for decades without fear of rubbing the letters or logo off.  Well, I should hope so.  I would expect to be able to keep this high polish finish looking good at this price point.

The feature I like best is the input volume control.  This allows me to connect my CD player directly to the amps without a preamp.  Martin DeWulf of Bound For Sound wrote a review of these amps that clued me in to this innovative feature.  The other plus for the input control is the convenience of being able to change speaker cables, interconnect cables, speakers, and other components without shutting the amps down.  I like to do lots of comparisons and equipment swapping and I get tired of shutting down the amps to protect the speakers and then waiting for them to heat up again.  This way, once I get them hot they stay hot and ready for instant listening tests.

The owner's manual is very easy to understand.  The tube biasing is simple and the adjustments are amazingly stable.  The tubes are adjusted separately so you don't have to buy matched tubes or hope the tubes age at the same rate.  The bias trimmer is a super accurate 15 turn Vishay pot that can set the bias exactly with a digital volt meter.  The designer is obviously an exacting tweak like myself.

I would describe these amps as very involving and enjoyable to listen to.  I don't get tired of listening after an hour.  I find myself listening for many more hours than I used to.  I'm looking forward to buying more CDs.  These amps worked superb on jazz, rock, folk, classical, and even reggae.  I love them.