[Dramlin]

I got mine from Mouser:
https://www.mouser.com/ProductDetail/Analog-Devices/AD827AQ?qs=/tpEQrCGXCy0eTwVO1turw==

Regarding AQ vs SQ, I've been curious about that too, especially with how much of a price difference there is. According to the data sheet the AQ and SQ should behave the same, with the main difference being the working operating temperature. Mouser also says there is a difference in the minimum voltage, but that isn't reflected in the data sheet. Overall I'd bet they sound the same, but no way to know for sure without trying it.

 

[Dramlin]

Finally finished the first elimination round of the op amps I'm testing. This entirely subjective testing was done by putting an op amp into the XD-05+, then listening to test tracks over about a days time for each op amp. During the testing I would compare the sound against a static reference (Ibasso dx120 in this case) to make sure there was always a single point to go off of. With that I can share which Op Amps that (in my opinion only) either have bad sound flaws, or are just plain mediocre at best in the XD-05+ design. Those are..

Op Amp	Single/Dual	Sound
AD712	Dual	Mediocre
NJM4560	Dual	Mediocre
LF353	Dual	Mediocre
OPA2132	Dual	Mediocre
LME49720	Dual	Mediocre
LM4562	Dual	Mediocre
NE5532	Dual	Mediocre
TLO52	Dual	Mediocre
LM833	Dual	Mediocre
OPA1612 (Stock)	Dual	Mediocre
NJM4558	Dual	Bad
NE5534	Single	Bad
OPA134	Single	Bad
AD823	Dual	Bad
NJM2068	Dual	Bad

I've got details on each of these, but usually the mediocre ones are a bit dark in the tonality, lack detail, and/or are just plain boring to listen to. The bad ones are veiled, muffled, or have other serious issues that make them sound worse than stock.

Testing is ongoing with the rest of the Op Amps that had great qualities and overall sound. Those are AD827AQ, Muses01/02/03, Burson v5I, OPA2227, OPA2228, RC4558, OPA2134, AD711, OPA627, NJM2114, OP275, LT1122, OPA604, OPA2277, and TL0171. If I had to pick favorites at this point I'd say AD827AQ for those looking for neutral/transparent, Burson v5I for those looking for a bit of a tube sound (lush, mild rolled treble, not tonally neutral but fun and detailed), and any of the Muses for those looking for maximum clarity and separation. Lots of good in the rest of the chips though, as several of the others are also impressive, needing lots of additional testing (RC4558 and OPA2228 come to mind). Testing continues..

 

[L@eric]

Finally finished the first elimination round of the op amps I'm testing. This entirely subjective testing was done by putting an op amp into the XD-05+, then listening to test tracks over about a days time for each op amp. During the testing I would compare the sound against a static reference (Ibasso dx120 in this case) to make sure there was always a single point to go off of. With that I can share which Op Amps that (in my opinion only) either have bad sound flaws, or are just plain mediocre at best in the XD-05+ design. Those are..

Op Amp	Single/Dual	Sound
AD712	Dual	Mediocre
NJM4560	Dual	Mediocre
LF353	Dual	Mediocre
OPA2132	Dual	Mediocre
LME49720	Dual	Mediocre
LM4562	Dual	Mediocre
NE5532	Dual	Mediocre
TLO52	Dual	Mediocre
LM833	Dual	Mediocre
OPA1612 (Stock)	Dual	Mediocre
NJM4558	Dual	Bad
NE5534	Single	Bad
OPA134	Single	Bad
AD823	Dual	Bad
NJM2068	Dual	Bad

I've got details on each of these, but usually the mediocre ones are a bit dark in the tonality, lack detail, and/or are just plain boring to listen to. The bad ones are veiled, muffled, or have other serious issues that make them sound worse than stock.

Testing is ongoing with the rest of the Op Amps that had great qualities and overall sound. Those are AD827AQ, Muses01/02/03, Burson v5I, OPA2227, OPA2228, RC4558, OPA2134, AD711, OPA627, NJM2114, OP275, LT1122, OPA604, OPA2277, and TL0171. If I had to pick favorites at this point I'd say AD827AQ for those looking for neutral/transparent, Burson v5I for those looking for a bit of a tube sound (lush, mild rolled treble, not tonally neutral but fun and detailed), and any of the Muses for those looking for maximum clarity and separation. Lots of good in the rest of the chips though, as several of the others are also impressive, needing lots of additional testing (RC4558 and OPA2228 come to mind). Testing continues..

After I installed the AD827SQ OPAMP to the XD05 two years ago, I was reluctant to replace it. Although I tried V5i-D for a short time in the middle, I couldn't make me decide to change the idea of AD827SQ, because I still like the sound performance of AD827SQ more.
Until the beginning of March this year, when I bought XD05+, I also found another good OPAMP---Muses 8920 that attracted me. Now it is Muses 8920 that has always accompanied XD05+. If you haven’t heard of this Muses 8920, it’s absolutely do not miss it!
https://www.head-fi.org/threads/xdu...introduction-impressions.789886/post-14261722

 

[WoodyLuvr]

XDuoo XD-05 Plus Black Edition + 05BL Pro (DAC HeadAMP w/ Bluetooth Module)

There is a very minor channel imbalance (favoring the right channel on mine) from 9 o'clock to 9:30 on the pot... however, that is well below any listening level at any gain setting with any of my earbuds. There is absolutely no background noise to be heard at the low and medium gain settings... though on high gain I can hear a faint hiss beginning @ 2 o'clock. This lil' amp is surprisingly powerful... listening volume is between 11 and 1 o'clock at low gain with any of my earbuds. Fortunately for me the 6.35mm jack (previously reported as being of low quality) is very nice on my unit so no complaints there. Bluetooth functionality has worked flawlessly with both my PC and smartphone; range is well over 10 meters. Both the XD-05 Plus and 05BL Pro were recognized immediately by WIN10 with no drivers required. Very well made headAMP with solid and smooth feeling switches, inputs, and volume pot.

 

[WoodyLuvr]

After I installed the AD827SQ OPAMP to the XD05 two years ago, I was reluctant to replace it. Although I tried V5i-D for a short time in the middle, I couldn't make me decide to change the idea of AD827SQ, because I still like the sound performance of AD827SQ more.
Until the beginning of March this year, when I bought XD05+, I also found another good OPAMP---Muses 8920 that attracted me. Now it is Muses 8920 that has always accompanied XD05+. If you haven’t heard of this Muses 8920, it’s absolutely do not miss it!
https://www.head-fi.org/threads/xdu...introduction-impressions.789886/post-14261722

Does the MUSES 8920 play nicely in High Gain like the AD827AQ/SQ?

 

[L@eric]

Does the MUSES 8920 play nicely in High Gain like the AD827AQ/SQ?

I always use High Gain on XD-05+, because my earphones are 600 ohm Beyerdynamic DT-990 & 300 ohm Sennheiser HD-800, so it is great for Muses 8920 to play with High Gain!
Compared with the AD827SQ, Muses 8920 the sound field is more magnificent, the interpretation of high and low bass, dynamic and transient explosive power is more amazing, I think Muses' performance will be amazing.

 

[Dramlin]

Just some housekeeping on a few items.

1) A few posts back there was a question on if there is a sound difference between AD827AQ vs AD827SQ, and from the data sheet I had assumed they would sound the same. I've now listened to both extensively and I was incorrect, they both sound quite different. In my opinion the SQ is a more refined version of the AQ. The difference being that the sound becomes a little thicker with more natural decay, stage depth increases a little bit, instrument separation is increased, and detail is increased. The AQ still sounds quite good, besting almost every other chip I've tried in sound quality, but the SQ is better in my opinion.

2) There's been a few questions on if the stock 6.3mm to 3.5mm adapter degrades the sound quality on this amp. There's 3 things with this:
- I've had 2 XD-05+ units, and both of the adapters I received sounded different from each other. So, there is variation in what is being supplied.

- My best stock adapter does degrade the sound a very SMALL amount. If I didn't have a slightly higher quality adapter I would have never known this. It's such a small amount though that I don't think most will notice, and in my opinion it's not worth trying to find a better adapter unless if you are sure that your stock adapter is causing issues, or unless if you are determined to squeeze out an extra 2-3% sound quality out of this amp.

- In searching for a 'better' adapter, the only high quality off-the-shelf ones I could find were from Furutech. Furutech has both Gold and Rhodium connectors that I decided to try. Reading the description on the back of the packaging states that they are cryogenically treated to improve electrical conductivity. Cool, With all that work they must sound great! I tried them and found that they are garbage, far worse than any of the cheap stock adapters I have that came bundled with various items. The Furutech gold plug decreases sound quality quite a bit, making every note fuzzy and changing the tone of the sound to be darker than neutral. The Rhodium thins out the sound dramatically, making things overly bright without adding any additional benefits vs stock.

 

[WoodyLuvr]

I have now used all possible available inputs and am very pleased with all. Currently, using the AUX IN option straight from my motherboard's Realtek ALC1150 DAC driven 3.5mm line output. No issues at all. Excellent battery life nearing more than 26 36 hours with earbuds.

XDuoo XD-05 Plus Black Edition HeadAMP driving my Blur 美魔女 Beautiful Witch "Dark" (300Ω) ear buds:

 

[Ultrainferno]

The xDuoo XD-05 Plus has just made it to our best DAC/AMP list
https://www.headfonia.com/xduoo-xd-05-plus-review/

 

[WoodyLuvr]

- My best stock adapter does degrade the sound a very SMALL amount. If I didn't have a slightly higher quality adapter I would have never known this. It's such a small amount though that I don't think most will notice, and in my opinion it's not worth trying to find a better adapter unless if you are sure that your stock adapter is causing issues, or unless if you are determined to squeeze out an extra 2-3% sound quality out of this amp.

So what brand and model is your slightly higher quality adapter?

 

[Dramlin]

It's custom. I took an Oyaide HPC-62SRH cable, cut the cable about 4 inches from the 6.3mm plug, then added an Oyaide J-3.5SR female plug to the cut end. The only difference from the stock adapter is that the sound is fuller now. Guitars (and all other instruments) now have the appropriate decay vs just being cut off about halfway through the normal decay. End result is that all music has more weight and ambience to it. The improvement is that small, but I'm hellbent on turning this portable amp into one that sounds like a proper desktop amp.

 

[WoodyLuvr]

...I'm hellbent on turning this portable amp into one that sounds like a proper desktop amp.

I'm with you!

 

[GUNHO]

I just bought a xD 05+ for $125 and I'm looking at rolling op amps. How many does this need? One or two ?

 

[Dramlin]

Your choice. The plus model supports two single channels, or one dual.

 

[GUNHO]

Is two singles or one dual better.