McIntosh MA2275 - opinions

Your McIntosh C22 Preamp is totally tube. It's RIAA phono eq and phono 'low' level signal boost, up to 'high/line' level are done by tubes, then sent to any amp, in your case a tube amp with 1 set of inputs.

A moving magnet LP cartridge (most common) sends a 'low' signal out to be processed by an RIAA Phono Equalization curve (bass boosted/treble cut), somewhere, then it's signal strength boosted, somewhere, up to 'high/line' level. (original ceramic cartridges sent 'high/line' level signals straight to the amp.

Amps amplify any 'line' level signal. Amps have 1 set of inputs, integrated amps have multiple inputs which allows several line level sources to go directly to the integrated amp. They often have volume controls, some remote volume. You use one input for the preamp's selected output to go into the amp. All pre-amp output is 'high/line' level strength.

Some integrated amps have passive pass thru for preamp signals to bypass all switching and volume circuits. In this case the pre-amp's volume is used, not the integrated amps volume control.

Traditionally, the low level cartridge output is sent to a preamp phono 'low' input, and the preamp has it's own RIAA phono eq circuit and subsequent phono signal boost up to 'line' level, then off to the amp.

These days, the phono preamp (RIAA eq and signal boost) may possibly be located within a TT, The TT then sending a 'line' level strength directly to an integrated amp (amp with multiple inputs), or, into a 'line' input of a pre-amp, then on to the amp.

My TT has a switchable internal preamp, I can use its switch in 'line' position, or send cartridge signal 'phono' position. Using SS C28 preamp, I preferred the TT preamp, now using tube mx110z preamp, I prefer the mx110z's phono preamp.

Moving coil cartridges produce a very low signal strength, and require a signal boost first, up to the moving magnet signal strength, then that is sent somewhere for RIAA phono eq, then boosted again up to 'high/line' signal strength to go to an amp.

McIntosh amps have switchable signal strength inputs, one is 2.5v to match their preamps which output 2.5v.

RIAA phono eq is how LP (long playing) records were achieved.

During recording, the bass signals are cut, thus smaller/narrower grooves are needed/made by the cutter. Move narrow grooves = Long Playing.

At the same time, the highs are boosted, enlarging the grooves so the same size stylus can track the narrower bass grooves and the wider treble grooves.

It also separates the highs further from surface noise frequencies, like Dolby did later for tapes.

I forgot,

thus, for phono playback: the bass has to be boosted back to normal, and the highs have to be cut back to normal. That is what the RIAA phono eq circuit does.

If a TT cartridge output is plugged into a line level input (without RIAA eq or signal strength boost), it will sound awful, no bass, screechy highs, and low volume, needing more pre-amp/amp signal boost, pushing either or both parts of the system up into noise/distortion range, especially tube equipment.

Believe it or not, early CD's, (early players costing $5k), some of the LP masters went directly to CD without RIAA eq, and the horror stories about CD's sounding awful resulted.