Treasure rooms have a fast cut off...(Like...theme of TRoom is so short and smoothly swithching to Floor theme)...it's sound strange
(it's just started...maybe in future i'll find more)

in "back up" run (after picking up Dad's Note) i hear Touhou Theme and some times Isaac's reversed theme...if I'm wrong - correct me

Will look in to these.

The treasure rooms and the ascension music are both intentional. Treasure room music apparently plays until it's entire sound file is complete, base isaac apparently has sound files of just next to 5 seconds long so I remember I made mine only 5 seconds long of a few Touhou songs and lowered the volume to make it seem like it fades out when it should keep going. I can't let it play a full song in the treasure room because it would then proceed to play the full sound file and not fade out when you leave. You can actually test that part yourself in either base isaac or this mod by walking in to a treasure room and then quickly exiting to the title screen, it'll continue to play the treasure room theme until it ends, albeit a bit quieter. As for the Ascension path, I was wondering whether to add it in or just keep it as base isaac music, but it's just the title screen but reversed, so I made this ascension path song just the title screen but reversed. It sounds a bit funky though

Couldn't quite hear reversed Isaac's theme, but I'm going to keep looking out for it and see if there is something I may've missed.

@[SaS] Shion Yorigami, I can hear it now, fixed it.

@Cirno , sorry for not answering in time, but yeah...
I really wanted to listen to the theme in the mod folder myself, maybe it was my poor head that went crazy.
but you noticed it yourself, so it's a good thing.
Cirno isn't baka :З

about TRooms...maybe I'm just not used to playing with another musical themes yet and it "cuts" my ears.... like...some things is too spicy for them...i hope you know what I'm talking about

The Cathedral wasn't playing any music.

@Janoy Cresva, Fixed.

hello again, Try to fight with The Matriarch
when you kill his minion starts playing BAM theme, then cam after victory
but boss still alive...and this thing can happened multiple times during the fight

@[SaS] Shion Yorigami, helloooo. So I looked in to this, and had the exact strange sounds you did. I asked a friend and it looks to just be a bug with how the boss is coded, not the music replacement. So when you kill the Fistula looking things, the game thinks you beat the boss when in reality the boss is still alive. Dunno why that's a thing but it's also apparently a problem with Delirium as well, when you kill off delirium when he turns in to Larry Jr., Lamb, or the hollow the music will stop and act like you won too. No clue how to fix this, sorry.

i hope you'll figure it out, good luck Smart Cirno

hello again, icy-fairy :з
here's a problem...at Beast fight there's only a Beast's theme, i mean...at all horsemans and at Beast itself...playing only Beast's Theme (obviosly at Beast theme is louder, like "It's MY theme suckers")
also...that's a bug probably (here's a code NZLH 1L4R)... at Mom's fight, after i kill her, her theme still playing, even without BANG we talked about earlier

Edit: on that code i went at Beast fight...if needed

I reverted the ultra horsemen theme back to just one theme because it was waaay too bad of a transition. Also, I'll look in to the mom fight, to see if i can't figure it out.