Worked on a little project today. Swapped out the included 6550 for a Tung-Sol NOS. Lots of screws - 20 in fact! to remove the top plate.
Faceplate before work:

Included 6550:

Circuit boards showing the 6H30s:

Tung-Sol installed:

I am listening now. A little deeper and wider soundstage but I will keep listening and post sound impressions later. I was told it made a nice improvement even though it is only for power regulation. I've certainly come to learn even small things matter in audio.
Faceplate before work:

Included 6550:

Circuit boards showing the 6H30s:

Tung-Sol installed:

I am listening now. A little deeper and wider soundstage but I will keep listening and post sound impressions later. I was told it made a nice improvement even though it is only for power regulation. I've certainly come to learn even small things matter in audio.