Likely your amp is clipping. It is a well known design trade off of the O2. Either you need a source with less voltage swing or use low gain. The O2 clips from too high an input voltage for the gain used, not from the volume output.

Before you send them out the door to the next owner, you should try the James444 mod. It does improve the bass and confusion on busy music quite a bit. The mod is quickly and totally reversible and is very well documented by James444...

I'm looking forward to your impressions. I've been swapping between the XBA-Z5, MDR-7550 and HA-FX1100.   The FX1100 is a niche performer. It isn't an all-rounder, but it really shines with acoustic and close mic'ed vocals.

I'm been auditioning IEMs for the last week mostly at my desk, so:   PupDac > GS-1 > IEM   I'm lacking for portable sources, I have an HTC M8 and a Rockboxed Fuse, but I haven't been using those for auditioning over the last week. That is what I eventually will end up driving them with. I...

    Not yet. Untaped these have impressive enough bass. I actually think they have a bit more bass than the XB90ex. I also think the XBA-Z5 has equal bass to the XB90ex. I know that's a bit different from the opinions here in the thread. I'd rank the bass response and extension like this...

I don't know the mechanics of buying from overseas in the UK, but Amazon USA has 2 pair of the MDR7550 remaining, stocked in the USA, Amazon prime for $315 Amazon USA also lists 148 sellers of the EX800, almost all Japanese, starting at $207 w free ship.   It seems like USA availability is...

 I'm well into "new toy syndrome" with my Z5. I know enough about myself to know I can't give a good opinion about equipment until I've had it long enough for it be "old hat". There have been lots of examples of stuff that sounds great for the first week or two that I don't really care for...

Well, I gave in to the curiosity. My rationalization to myself was I haven't spent any money on audio toys in over a year. The two IEMs I have been wondering about are the XBA-z5 and the JVC HA-FX1100. On the JVC, I have a bit of expectation bias because I've listened quite a bit to my...

I've read this whole thread (and a couple others) and I'm interested in some of the source discussions as well. I only use my HTC M8 or a Sansa Fuse with a Pico slim for my portable rig. I have good balanced desktop gear - GS-X mk2 and DIY dynalo Mk2 - and I think I'll spend some time with new...

I've got a question for the Z5 crew here. I'm going to spend some $$$ on IEMs in the next few months, say $1000. I've been collecting mid tier IEMs for 10 years or so, so this purchase is more to add contrast to what I have, not as my only IEMs. I have my end game home set ups and only use...

What are you using to power the O2 ?   I wouldn't go so far as to call it a defect, but the O2's has unusual clipping that depends on rail voltage and input signal voltage. If you are sure you are clipping in the amp section, you have rails running too low for the input and gain. That is the...

I don't know of anyone with a build currently in progress. I've had one up and running since October. It's my grail headphone amp.   If you are considering doing a build yourself, I'd encourage it. The build, in and of itself, is no harder than the original dynalo or any of several other...

I ordered 1 as well. A nice option would be to offer the complete kit without the enclosure, like how the PuP was offered. I can see building several of these to integrate into one case with a PuP or O2/Odac. I'd be a buyer of a couple more without cases.   Thanks for another great, ready...

      Actually, this is a bit confusing. The O2 has very unusual clipping behavior and clips *only* based on the level of the input. The O2's volume control has no effect at all on clipping behavior. The 7v / the output voltage level of the source is a useful rule of thumb, but brings up a...

Very nice review, but it may cause some unintended spending on my part. Thanks very much for taking the time to post it up, it's useful. I currently use a x-sabre > GS-XmkII > HD800 as my dynamic set up. I'd be curious on the opinions of the three amps driving HD650 and using classical...

Class A means the output transistors are biased "on" with a set bias current whenever the amp is on, even when there is no input signal. The GS-X will use about the same power and generate the same heat regardless of load *until* it is pushed hard enough to fall out of Class A. Falling out of...

  That power supply is AC input, 16V DC output. According to the online specs: Input: 120V AC 60Hz 17W Output: 16V DC 750mA That won't work at all for the O2. It requires an AC output to the O2. ~16VAC give or take.

I'm finishing up a SUSY dynahi and SUSY dynalo. I bought the dynahi boards from a lil knight group buy and I had the dynalo boards made from the publicly available gerbers by Seeed studio. I wouldn't hesitate to order from Seeed again for any design with gerbers available, like the dynahi. All...

I'm currently using X-sabre > GS-1 > HD800 until my GS-X arrives (hopefully next week or two). Out of the set-ups I've heard the HD-800, that's my favorite. I haven't seen one offered used in a while, but a G-lite or a good DIY dynalo can be had sometimes for cheap and can drive the HD800 well...

Any updates ?      

Chicago Can-Jam, maybe the last real Can-Jam ? Hope not. I got to listen to KG's T2 at the Chicago CJ. I still wonder if I heard what I think I heard; the best amp + headphone combo I've ever heard or ever will hear. There is something to the T2 that is just a touch more than the BHSE. The...

  Now that is interesting I've seen your results in the doodlebug thread for the PuPdac without the doodlebug. Did you happen to run the ODAC without the doodlebug? I had made an assumption that the ODAC might benefit from the doodlebug more than the PuPdac in a typical setup because the...

JVC HZ-FXD70     Audio Technica ATH-CKM500   I actually own both of these and I get pretty regular use out of them in spite of owning more expensive stuff. Both are on the bassy side of neutral and have very good resolution, headstage and blackspace around instruments. Both have huge...

I jumped the gun on a ODA PCB group buy and made an order for 10 ( in white ). It isn't a cheap amp to build, with all options, my total parts were ~$250 for 1. It appears to go a long ways towards eliminating the weaknesses of the original O2 for desktop use IMO.   The PSU section on the...

I'll be home in Tucson on the first two weekends of Nov (2&3 9&10) and would definitely drive to Phoenix for a meet. I'll be away at work for the second half of the month though.