Almost all the Servo Controlled subwoofers i've heard are more musical. And yes, the Yamaha YST-SW1500 is ported, but give an opportunity to it. I'm sure you won't be dissapointed. I don't know what is the word in English for the big bass instrument that old jazz bands used to play, but in Spanish this instrument is called "Contrabajo" and in the Yammie it sounded very rich, deep, profound, very musical.
I heard a Velodyne with the same record and it sounded to me punchy and not as natural as the Yamaha did.
Just a suggestion.