Loud does not equate to sound quality. The hd650 needs a good source to really get it's great qualities out of it. I havnt heard the 650 on the ifi, but I know it will give it better sq over that fiio a3. The thx00 ahouldnt scale a whole ton, i have a d2k which is similar, but they do sound more controlled and cleaner out of the ifi than straibht out of my fiio x3. If youre planning on continuing down the audiophile route, the idsd bl is a fantastic purchase as it really is a Swiss army knife and adapts to many rigs. I just can't see myself ever selling it, it's just too good of a piece of gear for the price, and a great multiuse gem FOR ME. Value of an audio purchase is always going to be subjective and individual user based, but knowing how the hd650 sounds on a mediocre rig compared to something of more substance and quality, it's worth the price difference, and I have yet to read anyone saying the black label wasn't a good pairing with their hps, it's done well with everything I have, and that I've tried it with. If you can grab it on Amazon with that 30 day return window then it's a no brainer.