Solutions For A Lossless Signal Path From USB port to wired headphones.

WWH

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Jan 31, 2024
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I am interested in lossless music using headphones and my WiiM Amp. I am asking how people are using to using headphones with the WiiM Amp USB port.

I just need a reliable way to use a completely wired signal path from the WiiM Amp to my headphones.

Right now I am using:

WiiM USB Out ——> in-line DAC 3mm jack——> W&B Px7 S2e headphones analog input

The Px7 S2e volume controls in Bluetooth mode do not function in wired mode by design.

The DAC is a Fosi Audio DS2. I have two problems.

First, the analog audio output is unusually low. To get reasonable sound levels the WiiM volune has to be increased from the ~ 1 LED light I use with my Polk S4 speakers (91 dB efficiency) to ~5 LEDs. The Fosi has a bulit in amplifier which is set to 100% (128 mW). When I use the standard iPhone USB-C – 3mm dongle the sound levels are smilarly low.

The volume is low when I connect the WiiM USB directly to the Px7 S2e internal DAC (also USB-3). The audio output levels for all these configurations is normal using a direct connection to a USB-C iPhone.

When the Px7 S2e internal DAC (also USB-3) is directly connected to a USB-C iPhone, the volume level is normal. When the Fosi DAC is connected to a USB-C iPhone, the volume level is normal.

Second, the Fosi DAC’s connection the the Wiim is unreliable. When a signal is present, the headphones automatically switch from Bluetooth to wired mode. With the Wii Amp I never know if the initial connection or reconnections will work. The heaphones behave as though there is no signal. Eventually they will connect. But there doesn’t seem to be a reproducible way to make them connect and, or reconnect. When connecting an iPhone USB C port, the Fosi DAC always connects and stays connected.

These problems occur with all the WIiM inputs I use (internet streaming, MacOS Apple Music to WiiM via ethernet, WiFi and TossLink using an Apple Airport Express or Apple TV Gen 3 Rev A.

I have used different sets of cables and used cables with and without USB A to USB C converters to no avail

The WiiM Amp USB output spec is 5V. Unfortunately I don’t have equiptment to measure my Amp’s output voltage.
 
Hi,

I did read the entire post, but got confused with all the permutations and didn't feel like drawing it to understand better!
Is the common volume issue the fosi? 128 mW is quite low and might well explain why you have to turn the amp up loud.

I use the usb output of both an amp pro and an ultra into headphone dacs such as the rme adi2, fiio k11 and smsl su9.
On medium gain in the HP amp I'd probably have the HP amp at about half volume with the wiim amp / ultra at full volume for pretty loud listening.
 
Thanks for your reply.

Initially I thought the Fosi Audio DS2 was suspect.

It turns out both the Apple USB-C – 3mm dongle and the onboard Px7 S2e headphone DAC require similar high WiiM Amp volume levels (4-6 LED lights).

It is useful to know you also use the WiiM Amp and the Ultra at full volume with the USB output.
 
This might help or might not.

A few years ago I was looking for a simple USB DAC to use with both my iPhone and a pair of wired B&W P7s and also with a Pi and the same B&W P7s. I tried a number of well reviewed but relatively low cost DACs including a HiFiMeDIY Sabre. The volume when used with the iPhone was just too low. The same applied to the Pi but as I had control I was able to access alsamixer and permanently increase the output volume. The main issue of the iPhone remained until I tried an Audioquest Dragonfly - in both use cases it was significantly louder by design.

My advice then. If you are able get an appropriate USB cable for your phone, load it with some music and test with the Fosi so you get a good idea of the output level. Then take the phone and your headphones to a HiFi retailer and test the various DACs that are available. You might be surprised at the range of different levels that various DACs will output.
 
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