Hi, I got mine Meridian Explorer today. Maybe it's not my lucky day today because I have bad feelings about it.
 
Tried the headphone out and it does sound a little off compared to my ODAC/O2. Balance is a little strange - I hear a lot of bass, which you would think is ok (though not as tight as I like it), but it is almost overkill on very bassy headphones. The bass overpowers everything imo. Mids seems more forward. There is treble but it is very slightly withdrawn. Overall balance seems kind of off (at least compared to my ODAC/O2).
 
Ok so I know of the somewhat high output impedance and wanted to try the line out feeding my O2 amp. This was the main reason I bought it. Now it seems more balanced but on occasion I hear distortion. I try to figure out why I hear this. Tried different USB cables from my Lenovo T61 but no change. Tried unplugging power cable to laptop (running on battery) but still something is a little off.
 
So I thought maybe this is so superdetailed that Spotify Premium (320 kbit OGG) isn't good enough of a source. Tried different kind of FLAC:s 24bit/16bit 44.1/96/192kHz, but still I sense that something is a little off. This testing was made with my Hifiman RE-ZERO and Hifiman RE-400 IEM. So I switched to my Mad Dog. Seems like it got better as time went by, maybe it needs to heat up or something, but still I sense that the bass is really loud that it distorts on very bassy songs like Massive Attack - Protection.
 
Maybe the O2 isn't a good match coupled with the ME? I don't know but I haven't had any problems previously with my Dacport LX, Dragonfly running of the same USB-port coupled with O2.
 
Also I don't like the USB-input on the ME - why is it upside down (well at least comparing to my other portable DAC/AMPs)
 
I hope that it gets better with time, burn in or something. Otherwise I like it - it is very detailed (but still prefer ODAC/O2 a little more imo)
 
Update:
I hoped the distortion would dissapear but it didn't. Somehow it is only present for me when I use line out on the ME. When using the headphone output I didn't hear the distortion at all. I can only hear distortion when playing music with lots of bass that's why I was only hearing it on some occansions earlier. I have followed installation procedure for a PC (ME website). I use Windows 7 x64. Checked the installation folder (Program Files\Meridian Audio Ltd\USB2_audio_driver_v2-1) and I can see several filenames containing 'x64' so it should be the correct drivers that has been installed.
 
Update2:
I don't have many external amps at hand. Tried my old Fiio E11 and somehow there was no distortion so I guess line out on the ME must be functioning ok after all. Maybe there is something faulty with my input on my O2 amp? Tried coupling it with my Dragonfly and heard no distortion at all, working ok. So I have some issue with the ME line out connected to O2 amp input. Can't figure out what the problem is. Tried different USB-ports no change. I use EHP-O2D, will be getting a standalone O2 amp (EHP-O2) soon. Hope there is some difference.
 
Note. Something I noticed that you should be aware of when switching between headphone output and line out. They both should output at the same volume level all the time so if I use line out I have to set it to 100% volume, but when switching to headphone output it is still at 100%. If not turned down before using headphones well you can probably figure out what will happen.
EHP-O2D

Quote:

deni5 said:

-
 

Click to expand...

I (and probably quite a few others) would absolutely love to read your impressions/comparison between those 4 dacs

Quote:

deni5 said:

Also I don't like the USB-input on the ME - why is it upside down (well at least comparing to my other portable DAC/AMPs)
 

Click to expand...

 
This bothers me, too. You have to twist the cable to get it to face up, but the cable is so short it wants to torque it back, and the device is so light that it rolls with the torque on the cable. Such a simple thing, but annoying, and casts another shred of doubt on the thoughtfulness of the implementation. Of course a longer cable will solve the problem, which I'll have to get anyway, because I use a riser for my laptop. 

Quote:

deni5 said:

Hi, I got mine Meridian Explorer today. Maybe it's not my lucky day today because I have bad feelings about it.
 
Tried the headphone out and it does sound a little off compared to my ODAC/O2. Balance is a little strange - I hear a lot of bass, which you would think is ok (though not as tight as I like it), but it is almost overkill on very bassy headphones. The bass overpowers everything imo. Mids seems more forward. There is treble but it is very slightly withdrawn. Overall balance seems kind of off (at least compared to my ODAC/O2).
 
Ok so I know of the somewhat high output impedance and wanted to try the line out feeding my O2 amp. This was the main reason I bought it. Now it seems more balanced but on occasion I hear distortion. I try to figure out why I hear this. Tried different USB cables from my Lenovo T61 but no change. Tried unplugging power cable to laptop (running on battery) but still something is a little off.

Click to expand...

 
Can you try the headphone out and turn down the output from the ME? The O2 amp does not like a hot signal to the input (because of where the volume pot is placed in the circuit, the O2 voltage gain op-amp will clip). The LO from the ME could be a little too hot. I am not sure though. I can measure it of course to find out.

Quote:

purrin said:

 
Can you try the headphone out and turn down the output from the ME? The O2 amp does not like a hot signal to the input (because of where the volume pot is placed in the circuit, the O2 voltage gain op-amp will clip). The LO from the ME could be a little too hot. I am not sure though. I can measure it of course to find out.

Click to expand...

 


No distortion at all with headphone out connected to the input of O2 amp. I tried line out again and thought it might change if I turn the volume down but it didn't change anything. Set it to 0% on Windows volume control and it was still playing as loud so it is a fixed value then (although it isn't grayed out). If I use the headphone out instead with the amp won't I get the coloration issues? I haven't run into this problem before at all. Didn't know about the "hot signal" issue. Thanks for helping out purrin.

Quote:

purrin said:

The O2 amp does not like a hot signal to the input (because of where the volume pot is placed in the circuit, the O2 voltage gain op-amp will clip).

Click to expand...

 
What's a good input volume level for the O2?

You should be safe on low gain with wall wart and 2.0Vrms output from the DAC. Around 2.5Vrms, and you start to be pushing it. This is based on calculations and theory. Murphy's law applies in real world scenarios. I've heard from others the O2 clipping earlier - at less output voltages.

Quote:

deni5 said:

 If I use the headphone out instead with the amp won't I get the coloration issues? I haven't run into this problem before at all. Didn't know about the "hot signal" issue. Thanks for helping out purrin.

Click to expand...

 
Nope. The output impedance for the head-out is relatively high only for certain headphones or IEMs, but low for line-level signals. As long as the input impedance of the device being driven is multiples higher than the 47ohm output impedance of the ME, then it should not be a problem. The input Z of the O2 amp is probably over a hundred-thousand ohms. It's not uncommon for DACs/pre-amps to have output impedance in the hundreds of ohms (no K).

Quote:

purrin said:

 
Nope. The output impedance for the head-out is relatively high only for certain headphones or IEMs, but low for line-level signals. As long as the input impedance of the device being driven is multiples higher than the 47ohm output impedance of the ME, then it should not be a problem. The input Z of the O2 amp is probably over a hundred-thousand ohms. It's not uncommon for DACs/pre-amps to have output impedance in the hundreds of ohms (no K).

Click to expand...

Ok, so using the headphone output at 100% volume would be as good as using the line out - no degradation, correct? Thanks

Yes, in theory.

Quote:

purrin said:

 
Can you try the headphone out and turn down the output from the ME? The O2 amp does not like a hot signal to the input (because of where the volume pot is placed in the circuit, the O2 voltage gain op-amp will clip). The LO from the ME could be a little too hot. I am not sure though. I can measure it of course to find out.

Click to expand...

 
I read somewhere it was above 2.0Vrms (IIRC, it was more like 2.25Vrms).

Quote:

deni5 said:

Ok, so using the headphone output at 100% volume would be as good as using the line out - no degradation, correct? Thanks

Click to expand...

 
Well, under normal circumstances, the headphone jack output would have additional circuitry for power amplification and volume control, and therefor might not sound as clean....or maybe better put, the extra circuitry gives more opportunity for degradation of the signal.

Also, you can plug these into the input to your amp to reduce the voltage of the line out.
 
http://www.amazon.com/Harrison-Labs-Line-Level-Attenuator/dp/B0006N41AG/ref=pd_sim_e_1
 

Quote:

tyll hertsens said:

Also, you can plug these into the input to your amp to reduce the voltage of the line out.
 
http://www.amazon.com/Harrison-Labs-Line-Level-Attenuator/dp/B0006N41AG/ref=pd_sim_e_1
 

Click to expand...

Hi Tyll, thanks for your reply. The input on the O2 is single 3.5mm but I should be able to find something equally good that works.

Quote:

kingoftown1 said:

I (and probably quite a few others) would absolutely love to read your impressions/comparison between those 4 dacs

Click to expand...

Hi, I find it difficult to compare those but here is my impressions. To me all of them sounds good but in different ways. First I should say that I prefer almost cold (dry?)/neutral/very detailed/analyzing sound. I like the very slight warmness I get from my HD-600 when driven from my ODAC/O2, that's about it. Then again I can also like my warmer Mad Dog equally well. I also want a transparent/not to coloring sound that works well with many of my different headphones and IEM's - I listen to different ones in my collection almost every day, not attached to one that I listen to all the time.
 
So based on above information
1) ODAC/O2 - My main setup and preferred one. Some find it cold/sterile/overly detailed/aggressive/digital, but I happen to like this signature so it works best for me.
2) Dacport LX - I like it very much actually, but I sense I very slight softness to it, some may say better refined, but I like slightly more aggressiveness/detail.
3) Audioquest Dragonfly - Reminds me off my of ODAC/O2 in detail (both use ESS Sabre) but still I sense some softness to it, can't describe it but it reminds me a little of Dacport LX. I still like Dacport LX a little more, but not by much.
 
Then there is the Meridian Explorer. I haven't been listening to it that much as I have had a little trouble coupling it with my O2, but when using headphone out (100%) to the input of the O2 amp I got the following impression:
It sounded almost very different from the above. Very agressive in all regards. I haven't heard that much bass before. To some degree I find it is to much according to the balance that I'm used to (aggressive but not overly so). So in some regards if I had a better amp at hand it could have maybe easily won me over - it is something different that I'm not used to at the moment. It sounded a little like all parts of the sound - bass, mids, treble were boosted but equally well (very good blending) so no part of it stood out (then again this depends on how balanced sound signature the headphone you are using has but that was what I sensed imo). I can't place it anywhere from 1-4 because I have too little experience of it. All I know is it is different. It seems playing in another league - as some would say.
 
All I can say is that it is not a day and night change when comparing them to each other. All to me are good and well worth asking price. They all sound transparent and also I can't sense anything totally off balanced with any of them.
 
This is of course based on my preference. Some doesn't like sharper treble and would prefer the Dacport LX or Dragonfly. I guess if you really like playing loud and aggressive Meridian Explorer would be perfect.