PEQ headroom and optical output — moving from SqueezeDSP to WiiM

[inbox4]

I'm considering moving from LMS/SqueezeDSP on a Mac mini to a WiiM Pro/Ultra, feeding a Chord Qutest via optical. I want to replicate my PEQ setup including a −2 dB offset for Inter-Sample Peak headroom.

I have three questions:

1. Headroom — Is Pre-Gain (under Audio Input) the correct place to apply −2 dB ISP headroom, or should it be set elsewhere in the DSP chain?

2. Optical output — When PEQ and gain settings are active, is the processed signal transmitted via optical (and other digital outputs) to a downstream DAC, or does DSP only affect the analogue outputs?

3. Verification — Is there a way to confirm PEQ is actively processing during playback — a signal path indicator or similar?

Advice from anyone running WiiM as a transport with an external DAC would be especially welcome.

 

[hgo58]

I'm considering moving from LMS/SqueezeDSP on a Mac mini to a WiiM Pro/Ultra, feeding a Chord Qutest via optical. I want to replicate my PEQ setup including a −2 dB offset for Inter-Sample Peak headroom.

I have three questions:

1. Headroom — Is Pre-Gain (under Audio Input) the correct place to apply −2 dB ISP headroom, or should it be set elsewhere in the DSP chain?

Yes, that is the correct place but note that pre-gain and PEQ settings are per input source. I really don't think it is needed, as the WiiM processes the 24 bit audio internally using 32 bit.

2. Optical output — When PEQ and gain settings are active, is the processed signal transmitted via optical (and other digital outputs) to a downstream DAC, or does DSP only affect the analogue outputs?

The DSP, including volume control, work on all outputs.

3. Verification — Is there a way to confirm PEQ is actively processing during playback — a signal path indicator or similar?

On the Ultra there is a spectrum analyzer screen but else you should be able to hear the difference when turning EQ on/off

Advice from anyone running WiiM as a transport with an external DAC would be especially welcome.

Running an Ultra out on optical to active speakers. The speakers have a fixed DSP to create a flat response, so I use the Ultra RoomFit to match the room and the EQ (GEQ and PEQ) to match the music.

 

[Burnside]

The DSP, including volume control, work on all outputs.

Except bluetooth, it doesn't support EQ/PEQ for some reason

 

[inbox4]

Thanks for the reply, out of interest, what active speakers do you use with the Ultra?

 

[inbox4]

Does anyone think moving from my current asynchronous USB connection to the optical out of the Wiim would be a downgrade?

 

[hgo58]

Thanks for the reply, out of interest, what active speakers do you use with the Ultra?

I have the Wharfedale Diamond A2 speakers.

https://www.av.com/Speakers/Wharfedale-Diamond-A2-Active-Floorstanding-Speakers-Pair-White/4D7S

 

[Burnside]

Does anyone think moving from my current asynchronous USB connection to the optical out of the Wiim would be a downgrade?

Depends on the quality of the optical interface on your external DAC i.e. can it safely handle 24/192. Some do however prefer USB

 

[inbox4]

Depends on the quality of the optical interface on your external DAC i.e. can it safely handle 24/192. Some do however prefer USB

It’s a Chord Qutest and does support 24/192 over optical. The USB input is technically superior at the same sample rates, I wonder whether this audible in the real world?

 

[Burnside]

It’s a Chord Qutest and does support 24/192 over optical. The USB input is technically superior at the same sample rates, I wonder whether this audible in the real world?

Some have said they prefer usb because they can hear a difference ( @adias if I recall), but personally I don't - that could be down to my hearing, speakers or room acoustics. As usual with all these things, you really need to try these things out and decide which you prefer for your setup. One argument as to why it sounds better for some is that a usb connection allows the external DAC to use its clock rather than what some say is the poorer clock in the WiiM, but others will say that any competent modern DAC should be able to handle any jitter thrown at it and through the use of buffers and PLL use its own clock anyway. YMMV...