You didn't cause any, that happens on it's on around here. Was it a full moon last night? It is your post and you have every right to keep it on track. I like your high road approach.
You keep asking away, and keep us all updated on how you are going to proceed and what you end up with.
I did the exact same thing you did, but about 15 years ago and with a vintage McIntosh preamp. Found one in great condition,I had it restored and got many, many great years of enjoyment out of it. It was a very fun and educational process.
I'm glad I went that route to get into tube equipment. From there, when I "upgraded" along the way I knew what I preferred, what to listen for etcl. Most importantly it helped me understand what I could hear, and couldn't here, in other equipment and whether it was worth the price.
Once you get that integrated you can then start switching out tube brands and see if you can tell the difference between brand X and Y, and if you can, is it worth the cost.
If you love the sound the way it is you are golden, if it leads you to want to explore other stuff, that's a great journey too.
Glad you posted, sorry there was a little off topic diversion, but glad to see the usual great advice and suggestions.