I didn't use the tube much, but the crackle was there either way. I also could not turn it up very high. Even with mirage omd28 shaking the neighbors two floors down I couldn't turn it up anywhere near 12.
Peachtree has had my unit for over a week now, and I have no idea when it'll be sent back. I have to say the repair side is very unresponsive to emails, and it's not like I'm sending a bunch or asking a lot of questions. The customer service side is always great though.
I'm going to sell it if it ever comes back since I find the denon to sound the same to my ears. It has much better volume control and is more versatile.