This unit was meticulously restored. The best example of a 6100 that we have come across. In superb shape for a unit of this age.
From Reverb Review:
As far as performance, well these amps are infamous in their ability to play well with any genre of music. There is a ton of info available online. The phono stage has incredible detail and the tone controls allow for flexibility regardless of speakers and room setup.
The unit will ship in a brand new original Mcintosh MA 6100 box so as to arrive safely to the new steward of this unit.
From Audio Asylum Review
The MA 6100 is a 70-watt Vintage Pre/amp -Amplifier sold during the seventies. It replaced the 45-watt MA 5100 ($449.00) from 1966 and was itself replaced by the 75-watt MA 6200 ($1,899.00) which went until 1991. The 6200 was pretty much the same except it had an equalizer and anti-clipping added in response to the then new digital sources. I lived with the MA 6100 for over fifteen years, then had a MA 6200 for over ten years. I did not use the equalizer, and I can do not need Power Guard to keep from blowing out my speakers. Now I am back with the MA 6100. Both have Headphone amps and no meters.
The 6100 has dual concentric tone controls. They decrease turned to the left, flat straight up, boosted turned to the right. They function, but really they are just decoration and will never wear out from turning. The balance control reduces the signal to the opposite side it is turned, to give equal sound pressure to the listeners ears. The on/off switch, volume control has an audio taper curve. It is a modified logarithmic curve starting with a dead zone. When you turn the knob, you can hear the volume change.
I did not know much about the compensation switch except that it made the music sound better and I left it on for over twenty years. It converts the volume control to a loudness compensated control switch. The effect is to give a flat frequency response across changing volume levels by keeping the low and high frequencies volumes up as the main mid-section volume is reduced. The effect increases as the volume is lowered so that we still hear the full-frequency range at lower volume levels and flat response is obtained at full volume. The presence position boosts mid-frequencies.
McIntosh:> The compensation switch automatically provides the correct amount of bass required to compensate for the change in response of the human ear at low loudness levels. When the volume is reduced, the music will seem to lose much of its bass and some of its treble. This effect is due to the sensitivity characteristic of human hearing. The response of the human ear to bass and treble pitch decreases more rapidly than its response to pitch centered in the mid-tonal range.
One of the great things about the 6100 is the multitude of controls it has for trouble shooting just about everything. It has controls for putting each side separately to both speakers, mono to both speakers, or mono separately to each side, as well as stereo, and stereo rev.
For example. If one of your sides is silent you can quickly check if its the amp, by running a mono signal to both speakers. If one is out check your speaker wires. If the both work switch one channel to both sides, you will know in an instant if one side is out. Using the pre-amp/ amp jumpers you can find if the source is before or after leaving the pre-amp. These controls just make it easy to trouble shoot. Once you have them if is a pain to go without.
The 6100 was always easy to set up quickly to give great sound whether it was for a few months or over a decade. It has easy to reach switches for two sets of speakers. After about eight years in one location it picked up a hum I don't remember if it was the 6100 or the 6200. But it was handled by running from the ground binding post on the back, outside to a copper rod in the yard.
The back has outlets up the yin-yang. Once I got the speakers hooked on I never gave any of them any thought at all. The Preamp is really separate from the Amplifier even though they are in the same case connected by solid wire jumpers. The "U" jumpers can easily be replaced with "Y" jumpers to install a subwoofer. These Jumpers are very handy for trouble shooting, or modifying the sound.
Some very ill advised reviewers have suggested changing the jumpers for cables. I am not in a position to say if you can or can not hear a difference using aftermarket jumpers with your McIntosh. In my mind, to assume that you do, you also have to assume that the stock jumpers are in some way degrading and that McIntosh knowingly provides jumpers with their integrated amps that sound inferior. I do not have any basis or reason to substantiate these assumptions and they are not consistent with my conversations with the engineers at McIntosh.
My Mac's always had vented Walnut wood cabinets that looked good, balanced and protected the unit, and never gave any kind of trouble. If you leave it on all of the time, it uses about as much juice as a 50 watt light bulb. Size 5-7/16"H, 16"W and 13"D. Weight 34 lbs. Sells now for about twice what it did then.
Most of the features offers by Mac I do not need. I just need it to take the digital output from the DAC, and put it to the speakers without changing the sound at any volume. The true function of an amp is very simple, but we get confused with all the stuff wrapped around it. Newer is not always better, a lot of the esculating costs is for some new invention that you may never need or to solve some problem that you never had.
Just like with sports cars, it takes time for newcomers to realize the affordable way in to high end audio, is the pre-owned market. If the goal is to have it sound like it did in the studio, vintage studio quality audio is at least one way to go. What I find audiophile's are doing today is putting together systems so that they can change the original sound as if the stereo is one giant musical instrument, and they are doing the final mix. No two are the same, no-one agrees what it should sound like. Except they all agree that with two ears the surround sound debacle do not lend themselves to great audio. It has been dismissed, and the consensus is two channels, or two channels with a subwoofer is an efficient way to great sound.