Volume Adjustment

Maybe accurate 

The McIntosh MA252 utilizes a digitally-governed volume control that operates in precise 0.5 dB steps. The rotary volume encoder controls an internal precision resistor ladder, which ensures outstanding channel tracking and balance throughout its attenuation range. [1, 2]

For troubleshooting volume imbalances, you can make an even finer 0.5 dB step channel trim adjustment for left or right via the input trim settings. The bass and treble tone controls also utilize 1 dB steps for a maximum boost or cut of ± 10 dB. [1, 2]

If you are experiencing any channel imbalances, you can adjust the trim level or check if the source cables are seated properly:

I’m thinking your encoder is honker up

Also, imo EVERY audiophile should have test tones from a reputable source and an SPL meter…. And learn the basics of both..,

Thanks for the answers !  The volume control knob is smooth as silk and no crackling or popping. ( I have that issue on a MA-6500 I bought about 7 years ago and for which I just bought a can of Deoxit D5 but have not applied yet. Opening up the case was cake. Just a little hesitant on using the spray.)

And, yes, the Trim Controls work great and there are .5 db increases/decreases to Input Trim and 1.0 db increase/decrease for treble and bass which seem to be on target. 

SO . . duh . . the iPhone in my hand has a built spl app.  I will test 52 vs 53 volume setting and report back.  Problem will be I don’t have a sound source that is steady and a regular CD will have built in volume fluctuations.  Maybe I can find a volume test signal tone on Spotify. We shall see.  Over. 

Thanks for the answers !  The volume control knob is smooth as silk and no crackling or popping. ( I have that issue on a MA-6500 I bought about 7 years ago and for which I just bought a can of Deoxit D5 but have not applied yet. Opening up the case was cake. Just a little hesitant on using the spray.)

And, yes, the Trim Controls work great and there are .5 db increases/decreases to Input Trim and 1.0 db increase/decrease for treble and bass which seem to be on target. 

SO . . duh . . the iPhone in my hand has a built spl app.  I will test 52 vs 53 volume setting and report back.  Problem will be I don’t have a sound source that is steady and a regular CD will have built in volume fluctuations.  Maybe I can find a volume test signal tone on Spotify. We shall see.  Over.