I think I have an amp problem

I don’t know what is wrong, if anything, with your amp. But I note that this unit is now 24 years old and probably needs service, i.e. a tune up anyway. If you haven’t had this done, you should probably do so. If a ’problem’ exists, your techie should be able to find it and cure it.  

It does sound most probably the integrated amp needs service or replacement. As @newbee pointed out. I would try and verify it happens with the CD as well. 

Given the age of the unit, it could be as simple as a bit of oxidation on the controls, volume or input selection. Assuming these are not fancy relay based controls and the volume is a simple potentiometer, a good cleaning with De-oxit will do wonders. Same for input selection.

Clean the controls.  If it sounds the same, I would send it in.  If you run it to failure,  it could cause a severe failure.  I hope they have service in US.  Or replace.  

Without having the unit in to evaluate it sounds like capacitors are failing in the power supply.  Open up the cover and check to see if they are bulging.  Check for any burn marks on the circuit board or if they have any smell.  This is a very simple check but after that it needs to come to a repair shop.  We are in New Jersey if we can assist you.

Happy Listening.

Have you made any changes to your system lately that may have an associated effect? If so, check he polarity of your cables, especially your speaker cables. If not, I would borrow another integrated to install and compare. Good luck!

zlone +1

If it's really input-specific and occurring on more than 1 source, start with the source control knob.  Cables are less likely to be the issue, for the same reason, but it's possible that multiple sets are failing.

If that doesn't solve the problem: the phono section takes a different path to the power amp circuit.  However, you could try switching the cables between the CD and streamer and preamp to see if the problem follows the cables or stays on the same source setting.

I would not play it until I was sure what the issues are ... that is a great amp!

@OP Given the age of the amp it is most likely to be a power supply problem. The effect you describe sounds as if the phase of the signal is being temporarily affected which could possibly be a power drop on the supply rail on one bank of push pull transistors. The nature of the problem and the age of the amp would suggest an immediate trip to a technician. A problem of that nature is only likely to get worse with worse consequences for the amp - and for your speakers if the amp goes DC.

Thanks for all your insights, much appreciated. An FYI update: The same problem finally occurred when playing a CD - so the amp is now disconnected and will be taken to a tech tomorrow. I’m a little leery if invest too much money into a 24-yr-old piece of equipment but let’s see what the tech has to say. I really like the amp (and don’t want to buy a new one unless I have to). I will report back - thanks again, I appreciate this forum.