Thank you for your very exhaustive test. I generally share your analysis, both on the positive points and the weaknesses.

I read that for your test with a smartphone, you only used the UAPP USB Exclusive Mode application, Bitperfect.
I did the same. But I also tested with applications without a specific driver allowing Android to be bypassed.

In summary :
With applications that allow direct control of the DAC/AMP bypassing Android (UAPP, Neutron, MusicCenter), no problem.
With applications without a specific driver (Foobar, Poweramp), I get an unbearable hiss, very noticeable at low volume.
With Neutron, and even after activating Direct USB Access in the settings, I get an intermediate situation: no hiss, but the LED always red, regardless of the bitrate of the file read.
My phone is an Xperia 5III. Could this issue be specific to this phone?

@Mörchingen In my own usage, I have 3 devices used. USB 2.0 of Sony Xperia X Compact, USB 3.0 of LG V50 ThinQ (primary device) and Windows 10 USB 3.0. At any conditions I subjected my Link2 BAL, I does not encounter any of the issues you mentioned. And on top of it I use anything between 22 Ohm hybrids to 600 Ohm headphones. Three of my test IEMs which are super sensitive would have picked up the anomalies if Link2 BAL have issues with noises. So perhaps it's the host you are using

@TooPoorForHiFi Out of 109 dongles I own and tested, Link2 BAL is among the top 5 on my personal favorite list. That top 5 starts with CEntrance DACport HD, Cayin RU6, Lotoo PAW S2, Ovidius B1 and now Link2 BAL. The difference between RU6 and Link2 BAL, it has double the power of RU6. But really quality wise on the technicalities they are pretty much similar - except that Link2 BAL has wider soundstage by a step or two. What RU6 does better is the timbral balance of actually sounding Analogue as opposed to Link2 BAL being close to analogue. And that is the X factor RU6

Nice review. Hey, can I ask you what cable you have attached to the ER4SR? Thanks

@InvisibleInk Thanks. The cable for my IEMs and Headphones are primarily VE Standard DI Copper 6N. The one you see in the pic is an MMCX version.

Very nice review! Thanks! In normal mode when driving highly sensitive IEMs, any detectable hiss noise?

@earfonia No noises as tested with my sensitive hybrid IEMs

if both 3.5 and 4.4 are occupied, does audio output simultaneously, or does it prioritize one over the other?

Is it a significant upgrade on the Ovidius B1 to warrant buying? Especially with regard to soundstage (because I assume quality of frequency reproduction would be at least as good!)

@misteral201103 No, Ovidius B1 will always have a special place for me due to the ethereal and airy lifelike timbral balance. Yes B1 is not as clean sounding as Link2 BAL, but it is special akin to appreciation to classic vinyl and tubes - analogue experience. Link2 BAL however does it better with soundstage and holographic spatial imaging, where B1 more classic left/right stereo sort of presentation

@misteral201103 Unfortunately I was unable to test plugging two plugs at the same time, my cables all equipped with somewhat fatty plugs and they have no room to sit together.

Hi there! Have you tested the Quadelix-k5 and do you have any thoughts about the sound quality vs Link2 BAL. Any generel thoughts about Bluetooth dongles? Want to upgrade from Ibasso DC03 which sounds good but to digital and crisp, thats why Im interested in the Link2 BAL but heard interesting things(10-band full PEQ) about the Quadelix-K5.

@aceopp No I haven't tried Qudelix 5K. It is a BT and battery powered DAC/Amp so it does not fall into traditional Dongle category. Furthermore I have no use for EQ or any artificial sound modifiers, so the features of Qudelix 5K is not something that interests me.

Alright! I have now got the Quadelix K5 to check myself... and the Ibasso DC03 was more lush, technical and I enjoy it more(even if the highs can be a little bit sharp), but EQ can be "good" on some "bad" headphones/IEMs and like me have it cabled to my phone, then BT can be better(not sound wise, yet) ex, when I workout(probably keep K5) . I was thinking to buy the DC05 but your and others review got me to order the Link2 bal.. think I gonna like that character and some good value for my money.

Sir, dongle madness is fine, but i think u should consider trying qudelix 5k atleast once. So that it ca be used as a reference. So that people like us get to know how good the dacs are. yeah hope u try 5k once . And include it separately with just star rating.
And as always great review. Really really awesome

@Lantern05 Qudelix 5K and FiiO BTR5 even 2021 version is no way near Sonata E44 which is close to Link2. Not worth going to these BT receivers as for best SQ unless you need BT.

Oh, thanks @abccpu. Recently i did purchase Abigail dongle dac and i felt that the sq is slightly better than Q5k which i own aswell. And could u tell a dongle dac that has similar sound signature/performance as the Q5k which i can use as a reference for future purchases

@OspreyAndy hey there, great review. Could you the elaborate meaning of digital dependence on the host? Does it change the phone volume when you push the buttons?

@WilliamCruz Yes it means the vol buttons will change the volume levels on the host, not independently

@OspreyAndy
Thank you