Mini-i Pro 4 (separate volume for headphones, skipping and glitch issues)

[Three Springs]

Hi, I recently purchased Mini-I 4 Pro (great product). However, some questions:
 
1.   I would like to listen to two headphones at once with a mate (HIFIMAN Deva Pro [18Ω 93.5dB] and HE560V4 [50Ω 90dB]) and noticed that the volume on both headphones (using 6.35 and 4.4) are quite different. Is there a way to control the volume of each headphone independently? I noticed here (6:27): 
that the old Mini-i offered this function. What about the new Mini-i 4 Pro?
2.   I have been using a male to two female 3.5 power splitter in the 6.35 jack to listen to both headphones at once. Lately, I’ve noticed that when connected to USB Audio (with USB-A), there would be the odd glitch or skip (I didn’t notice this for Airplay but havn’t tested it thoroughly). Because I have found this for youtube, foobar and iTunes, I’m guessing it’s from the Mini-I? Then, it started doing this even when I went back to a single headphone. Earlier today, I performed a software update and immediately after, listened to an album (with power splitter) for about 35 minutes with no problems. I paused it for 10 min, and when I resumed, it started skipping/glitching again.
 
Any help for a solution would be greatly appreciated.
 
 
 
 

[LI HUI]

Hi Three Springs,
1.Actually, even the mini-i Pro 3 doesn't have the function you want. You can see 2 volume decibles on the display, but the decibles of each headphone out changes at the same time. They can't be changed separately. With the mini-i Pro 4, we use volume numbers instead, the volume number related to 2 decibles, but only display 1 volume number.
2.Is the skip sound happened randomly? What computer were you using? Can you test with a laptop without power adapter (use battery power), or test with an Android phone as USB source?

[Three Springs]

Thank you for the response!
 
1.   This was a great function offered by the old mini-i Pro. Why was it removed? (Shouldn’t new technology be an improvement?) Is there any other way for me to listen to two headphones at once using the mini-I Pro 4 aside from using a power splitter? And is there no way to control volumes independently?
 
2. Yes, the sound skip/glitch is random. My computer is LENOVO slim 7 16ARH7 (only about a year old). I do not have an Android phone, but I tried test listening with battery power (for about 30 minutes on foobar), and interesting enough, the problem did not occur… What does this mean?

[LI HUI]

Thank you for the response!
 
1.   This was a great function offered by the old mini-i Pro. Why was it removed? (Shouldn’t new technology be an improvement?) Is there any other way for me to listen to two headphones at once using the mini-I Pro 4 aside from using a power splitter? And is there no way to control volumes independently?
 
2. Yes, the sound skip/glitch is random. My computer is LENOVO slim 7 16ARH7 (only about a year old). I do not have an Android phone, but I tried test listening with battery power (for about 30 minutes on foobar), and interesting enough, the problem did not occur… What does this mean?

Hi Three Springs， 

1. You may misunderstand me. I meant the mini-i Pro 3 doesn't have the function you need. It displays 2 decibles, but the 2 headphone outs CAN'T be adjusted separately.
   
2. So the glitch may come from your power mains, a power filter or a power conditioner may helps.
   

[Three Springs]

Hi Three Springs， 

1. You may misunderstand me. I meant the mini-i Pro 3 doesn't have the function you need. It displays 2 decibles, but the 2 headphone outs CAN'T be adjusted separately.
   
2. So the glitch may come from your power mains, a power filter or a power conditioner may helps.
   

1. I don't know about the mini-i Pro 3 but the mini-i Pro video review video I linked (please see 06:09 - 06:25) claims 2 headphones can volume match separately (between the 4.4 and the 6.3 - not between a single one through power splitter). Was that an even older model in the video? So the original mini-i had this function but not the newer ones? Why does it display 2 decibel numbers (volume) between the 4.4 Single Ended output and the 6.3 Balanced output if they can't be adjusted separately?

2. So what's wrong with my computer? Is there a way I can fix this before I make further purchases? What do you suggest?

[LI HUI]

1. I don't know about the mini-i Pro 3 but the mini-i Pro video review video I linked (please see 06:09 - 06:25) claims 2 headphones can volume match separately (between the 4.4 and the 6.3 - not between a single one through power splitter). Was that an even older model in the video? So the original mini-i had this function but not the newer ones? Why does it display 2 decibel numbers (volume) between the 4.4 Single Ended output and the 6.3 Balanced output if they can't be adjusted separately?

2. So what's wrong with my computer? Is there a way I can fix this before I make further purchases? What do you suggest?

Hi Three Springs，

1. Trust me, the logic of volume control of the 2 headphone outs are the same in the 2 models. (He is not saying the feature you want by the way. Watch the video again, please.) Take a note at the output icon on the left, headphone out and line out. The output volume of 6.35mm and 4.4mm are always consistent (they always has 6dB differences).
   
2. It may be because of the power mains, some interferences transmitted to your device and causes the drop out. The other way to verify this issue, bring the devices to another environment, e.g., your office or another one's home, see will it happen again.  Many factors may cause such problems. An example, one of the customer in China, as long as the compressor of his refrigerator starts or stops, his DAC drops out.
   

[Three Springs]

Hi Three Springs，

1. Trust me, the logic of volume control of the 2 headphone outs are the same in the 2 models. (He is not saying the feature you want by the way. Watch the video again, please.) Take a note at the output icon on the left, headphone out and line out. The output volume of 6.35mm and 4.4mm are always consistent (they always has 6dB differences).
   
2. It may be because of the power mains, some interferences transmitted to your device and causes the drop out. The other way to verify this issue, bring the devices to another environment, e.g., your office or another one's home, see will it happen again.  Many factors may cause such problems. An example, one of the customer in China, as long as the compressor of his refrigerator starts or stops, his DAC drops out.
   

1. I do see that when he turns the volume, both decibels change at the same time and are 6dB apart (okay). So does this mean if you change the volume for one output only (say the 6.35 up by 3dB), then automatically when you switch outputs, the 4.4 will also be 3dB higher by default to start?

2. Regardless of other environments, my priority is to get it to work properly at home. I notice the problem is most prevalent after a restart (of my laptop). When I restarted earlier, the skip/glitch would immediately be more frequent (on foobar) - even when I pulled the power cord and used battery power, and especially when I opened another program (such as Microsoft Word or Google Chrome). I even restarted the mini-i, but that didn't seem to help. It wasn't until 10-15 minutes later that it seems to have settled down a bit. Any reason why this is the case? And is there anything I can do about it?

[LI HUI]

1. I do see that when he turns the volume, both decibels change at the same time and are 6dB apart (okay). So does this mean if you change the volume for one output only (say the 6.35 up by 3dB), then automatically when you switch outputs, the 4.4 will also be 3dB higher by default to start?

2. Regardless of other environments, my priority is to get it to work properly at home. I notice the problem is most prevalent after a restart (of my laptop). When I restarted earlier, the skip/glitch would immediately be more frequent (on foobar) - even when I pulled the power cord and used battery power, and especially when I opened another program (such as Microsoft Word or Google Chrome). I even restarted the mini-i, but that didn't seem to help. It wasn't until 10-15 minutes later that it seems to have settled down a bit. Any reason why this is the case? And is there anything I can do about it?

1. Ignore the dB differences. That's because with the same signal from the internal DAC, the balanced headphone amp provides a higher gain than the unbanlanced amp. At any time, the DAC outputs the same signal.
   
2. That's the reason why we don't suggest listening to music through a computer. Computer is not a dedicated audio device. But a hifi audio device could be affected by the interference from computers easily. If the interference comes from the external of the device, we could do nothing.