I have 2 old Eagle 2 amps, as well as 2 Eagle 4's and a newly minted Eagle 2C. One of them I bought recently was an early s/n and "well used". It did the same thing when I powered it on. Here's what I suggest first: 1) Open it up and clean out th einside thoroughly. You may want to install a new power switch (you can get them from EKSC) or clean the existing onw with switch cleaner/lub from Ratshack or other similar product. 2) Check that the fuse is proper (7 amp slo-blo). 3) Power it back on and leave it on - 24x7 for at least a week. Play it during this time as long as it's operating properly. See if the noise returns after this time.
If it does - see the following from the EKSC Website:
IMPORTANT NOTICE:
If you own an older Eagle product, more than 10 years old, we STRONGLY recommend having all the electrolytic capacitors replaced. For Eagle 2 series amplifiers, we have a flat fee service with two year warranty. Please contact Eagle concerning other products. This is true no matter what brand of amplifier is involved. Failure to replace worn out electrolytic capacitors in any amplifier can result in catastrophic failure, possibly damaging the amplifier and loud speakers.
You may want to have the amp recapped and/or modded. Thet aren't cheap, but it's worth it. The Eagle 2C is a really nice amp even factoring the cost of the upgrade.
hope this helps.