"What is that incessant racket?"
Regulus sighed. He had no idea what his brother had brought home this time, but now their mother was on the warpath. And while the ensuing confrontation would likely be interesting to listen to, she was going to reach his door first. Fortunately, the truth would likely serve well, in this case.
So when she stopped outside his door, Regulus said, "I wouldn't know, Mother. You'd have to ask Sirius."
She swept on down the hallway, but Regulus didn't get up to close his door again. He was just as curious about what his brother was playing, if rather less inclined to start shouting about it.
The noise got louder, briefly - that must have been from the door opening - before cutting off with a nasty scratching sound.
"Sirius. You will explain this... this cacophony, and you will do so at once."
"It's new music, Mother. Band's called T. Rex. Didn't you like it?"
"I most certainly did not. On what grounds did you dare to pollute the house with this noise?"
"You can't destroy it."
"I can and I shall, unless you have an eminently convincing argument against it."
"It has provenance, Mother."
Regulus looked toward the door, both eyebrows up. That was an unusual card for Sirius to play in any argument - largely because most of what fascinated him had no pedigree their parents would ever find acceptable. And while Regulus was more inclined to agree with his mother's description of the supposed music's quality, he still wished he could see her reaction.
But he didn't wish it badly enough to attempt watching the end of the argument.
"Yes. It does. The singer went to Hogwarts - you can tell, if you look at some of the lyrics."
Silence stretched out for a good half a minute, during which Regulus wondered where that left the rest of the band in terms of provenance - and where Sirius had figured out to take this approach.
"...Well. I suppose, since you bring home little enough of any value, you might be permitted to keep this. However, do not play it at such volumes as you were. It disrupts the rest of the house."
Regulus almost went to congratulate Sirius, after their mother had returned downstairs. But he had no way of knowing where Kreacher was, and didn't want to spoil the moment by landing himself in hot water.