10 gauge power cord. Too much power for tube amp?

Just in case you didn’t, did you check the power cord for nicks? If the male and female ends are operable did yah look there too? This is 99.8% sure not to be it.

Did you switch cords? Tap tubes for microphonics? Swear a lot?

The amplifier is a Mc2301 from McIntosh that's giving blinking red lights after warm-up frequently. Power tubes have been replaced with new ones, maybe it's a signal tube. Sometimes it works fine, as long as amp stays on for at least a minute after warm-up.  

Power cord has nothing to do with the amp shutting down. The protection circuitry is kicking in. Don’t know how it’s wired but it usually senses overcurrent at the output stage. This can be caused by a failing power tube, a total loss of bias voltage or loss of bias at an output tube, an intermittent short in the output stage or a mismatch between connected load and speaker tap.

The power cable can’t generate power however as mentioned the wrong sized cable, I.e. too small can restrict power. Put the OEM cable back on and if the problem persists, contact McIntosh or at least Audio Classics. The problem is in the unit and they will suggest a possible fix or ask you to send it in for a check up. I have dealt with McIntosh many times over the years and they are great people to work with. They have an enormous pride in their products and equal appreciation for their customers.