I was disappointed in my McIntosh C15 when I first got it. I used to sell Mac gear in the late 70’s and it was fantastic.
When I looked inside the C15 I was not surprised to see an opamp had replaced the superlative design and engineering of old McIntosh equipment.
First, I replaced the stock opamp with brown-dogged opa627’s. I heard some of the magic of the old Mac preamps return with this tweak, but it was not anywhere near where it should have been.I then replaced the opa627’s with a dual Burson opamp with the V- and V+ bridged by an Angela 1uF tin foil capacitor.
The magic is there now in full force. Detail, resolution, soundstage, extension are there against a black background for a reproduction of the music that mimics a live performance.
I would not hesitate to recommend the Burson opamp to upgrade ANY other opamp for an impressive improvement in sound quality!