The item:

For sale is a good condition vintage Dynaco Stereo 400 Power Amplifier. Fully tested and in working condition. Slight mild hum on the left and right channels. Only noticeable if you have you ear right up against the speaker. These are not known for being dead quiet amps. No modifications on this unit other than replacing the RCA jacks with new gold plated jacks. 

Here is the work that was recently done:

• Replaced the aged RCA jacks with new gold plated RCA jacks from updatemydynaco.com;