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(Another) question about pass-through - active speakers edition

olinko

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Hi, I'm looking for confirmation from people who actually know something about the topic so help :)

So: I have the (very much wonderful and brilliant) HiVi Swans D300 active speakers. These have (among others) optical and coaxial inputs. As the speakers use DSP, my goal is to keep the chain fully digital from source to sound to avoid feeding the speakers analogue signal through a DAC (because the speakers would just take that analogue signal, convert it back to digital then again to analogue).

So, this is where the conundrum begins: I want to use my laptop as the source playing my local FLAC library via a WASAPI (event) in foobar to override any windows audio settings. I connected my laptop via HDMI to my LG CX TV which is then connected via optical cable to the optical in of the speakers.

My hope is that the combination of the WASAPI event and the TV settings set to 1) HDMI Bitstream and 2) digital sound out - pass through will together lead to an uninterrupted chain feeding my FLAC files (everything from 16/44.1 to 24/192) in their original format to the speakers directly and then allowing the speakers alone to process the signal

Reason why I'm asking this and why I'm skeptical this works: 1) I can normally play 24/192 FLACs even though the specs for the speakers themselves say they allow everything up to 24/96. Not sure if everything above that is completely unplayable for DSP active speakers or it's just not recommended (also, can optical cables even carry 24/192 signal? hmm)
2) this may totally be self-doubt and placebo, but I think the sound is slightly better when I play files off my FiiO M11 DAP via SPDIF out directly to the coaxial input of the speakers.
How I understand it is there should be no difference in sound as it's the speakers doing the processing, right? Or am I wrong

TL;DR the chain: foobar (WASAPI event)/laptop - HDMI out (Bitstream) to the LG CX TV - optical out (pass through) - HiVi Swans D300 optical in. The goal: getting my flac library uninterrupted and untampered with to the speakers while keeping the signal fully digital
 
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AnalogSteph

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So the speakers will accept 192 kHz from the M11? Even so, that'll probably get resampled to either 96 or 48 kHz internally... higher sample rates cost more processing power with few benefits, so a lot of DSP speakers / devices don't go beyond 48 kHz, a few even stick with 44.1 kHz.

It is not unusual for TVs to have internal digital volume control and stuff, so levels may differ from the M11, thus accounting for the differences you heard.

The bandwidth of a Toslink connection is a matter of optical transmitters and receivers used... with parts capable of 16 Mbaud you're generally limited to 24/96, while 25 Mbaud will do 24/192 as well. The optical connection itself would be capable of substantially more.
 
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olinko

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So the speakers will accept 192 kHz from the M11? Even so, that'll probably get resampled to either 96 or 48 kHz internally... higher sample rates cost more processing power with few benefits, so a lot of DSP speakers / devices don't go beyond 48 kHz, a few even stick with 44.1 kHz.

It is not unusual for TVs to have internal digital volume control and stuff, so levels may differ from the M11, thus accounting for the differences you heard.

The bandwidth of a Toslink connection is a matter of optical transmitters and receivers used... with parts capable of 16 Mbaud you're generally limited to 24/96, while 25 Mbaud will do 24/192 as well. The optical connection itself would be capable of substantially more.
When running the spdif out of the M11 into the coaxial in of the speakers, 24/192 files do play but they start to stutter pretty quickly, I haven't tried playing with that because I didn't want to push the speakers.

But generally, with the way I described it, there's nothing I'm overlooking? A 24/96 file played in foobar via WASAPI event will get to my speakers as the same 24/96 source?
I thought it'd be like "you're forgetting that HDMI always does X to the signal first and then transmits it out" so that's where your digital chain gets screwed up
 

AnalogSteph

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What exactly your TV is doing to the input signal obviously is anyone's guess. If in doubt you'll need a sound device with a 24/96 capable SPDIF receiver so you can take measurements e.g. with RMAA. (Choice among USB devices is rather limited these days, but e.g. a used SB X-Fi HD should get the job done if you don't feel like shelling out for a new Behringer UMC1820.)
 

ThatM1key

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I don't know what kind of laptop you have but I would see if the 3.5mm headphone out has a optical out in it.

Something like this:
gokuH.jpg
 
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olinko

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I don't know what kind of laptop you have but I would see if the 3.5mm headphone out has a optical out in it.

Something like this:
gokuH.jpg
Yeah that would be the best option, but unfortunately my laptop doesn't have a spdif out
 
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