Hello, all... I'm a novice to headphone amps, and I am looking for a little clarity on an issue with the Little Dot 1+ I just ordered... Delivery is still a few weeks out at most, but I've been looking at different tube sets for this amp... My issue follows: A few days ago, after ordering the Little Dot 1+ from Amazon.com through a Chinese vendor, I put this question to the vendor, who is listed as SHENZHENAUDIO… My question: Hello: One more question, if I may: If I decide to use the WE 408 A tubes in the Little Dot 1+, do I have to change the jumpers or pin-out or anything else like that?... Also, do you have a favorite op-amp change for these tubes?... I listen to mainly classical music, and I like a lot of airyness and definition... Not really a bass freak... ???... Thank you, and best regards, Mark. Answer from seller: Dear Mark: You mean use WE 408A in the Little Dot 6J1 version? If so, please don't do that. I used to change the tubes. But it smells bad for the amp. Please kindly check that. If you have anything, please contact me freely. Thanks and best regards, Tina. Now, since I’m a novice at all this, this has me worried… Are there different versions of the Little Dot 1+ other than just what tubes it comes with?... I thought one of the main features of this unit was that you can roll different tubes into it, with the caveat that you may have to change internal jumpers, which are supposed to come with the unit… So, I guess I’m asking for a little clarity here… Thanks in advance, and best regards, Mark.