I would suggest you check out Head-Fi as there is quite a following for the MG Head.
I haven't compared, but David Berning's MicroZOTL is a headphone/low power amp with a headphone jack and volume control. It is an OTL tube design with (2)12at7 input tubes and (2)6sn7 ouput tubes. It is fabulous. Costs $750 direct from Berning. About the size of a shoebox, 4 pounds, and doesn't get hot. Very reliable. Auto biasing. No fuss.
Do yourself a "HUGE" favor check out the Sugden Headmaster Headphone Amp.Operate's in CLASS A,unbelievable amp!!! Blow's away Headroom's Maxed Out Home at alot less,can be had for about 850.00 U.S.The sound is incredible,built like a tank. I know 2 people who owned the Headroom Maxed Out Home Amp,they sold there's when they heard mine.Picked this up on a buisness trip overseas,but they can be had in the state's. www.headphone.com said,they are looking into carrying them.If you hear this you will want it.Running Sennheiser 600,phones with Cardas Golden Cross innerconnects.Awesome!!!! Good Luck...
Also, if the above mentioned are a little to pricey, check out the excellent Wheatfield headphone amps.
I own an HA-1 (w/Senn. HD600's) and love it! All tube, PILLIOD transformer, built like a tank.
Here's a link to a review; http://www.northcoastweb.com/david/wheatfield/home.htm
can be purchased through "Headroom's" wb site (see under manufacture's list ander "H").