Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: I love these cans, but....

The bass response is unmatched. Period. I have noise canceling, open air, and closed air high-end phones and the bass response from the Vibes is exquisite compared to these. I love the way they sound... when they sound.I returned my Amazon pair because of a faulty jack making one channel cut in and out randomly.I just got my RMA pair with the promise that they have refined their manufacturing process, but out of the box, one of the bass channels is dead. This makes the sound space sound lopsided and empty on one side. I'm returning those now. One good thing is that the RMA has been a simple process and without hassle.