So the boxset has been out for some days, and I've managed to give it a spin to the trilogy. First of all, these albums are louder than the original, a bit more compressed. But they sound glorious. I was thoroughly surprised that Nattens Madrigal actually sounded good. Yeah, it still feels like it was all recorded with cheap microphones, but the guitars are cleaner, and the drums actually feel more real, like they weren't recorded 20m away from the studio - just around 15m or 10m.
Bergtatt is even more superb than before. It already sounded good for a black metal album, but now the guitars and drums rise up and shine - and with the great treatment of vocals, now I can really see that Gram had an outstanding talent for his young age. Didn't pay enough attention to Kveldssanger, but it sounds nice and clear. Never heard the original recording of Vargnatt, thus can't compare it. But it's middle way between Bergtatt and Nattens Madrigal in terms of sound quality.
All in all, a great remix of these classic albums. Although a bit loud, they sound better than ever, and Nattens Madrigal is finally listenable. Go and get them.