Hi, I’m trying to track down the cause of some poor sound quality in my setup.
When using the Wiim Amp Pro as a streamer to play Spotify, the quality is, in my view, excellent.
However, the sound quality is not as good when feeding the Wiim Amp Pro from my TV. It seems slightly veiled by comparison.
In my setup, the source is an Apple TV, plugged into my TV via HDMI. The TV then outputs the audio to the Wiim Amp Pro via HDMI ARC.
The output levels of the two inputs initially did not match, with a measured difference of around 12dB at the same volume setting, but I was able to dial this out using the pre-gain settings in the Wiim app, +10 for the TV and -2 for the Ethernet input.
My testing scenario is comparing Spotify audio, with the same track, at the same level using the Spotify app on the Apple TV, compared to Spotify via the built-in Wiim streamer. In this scenario the built in streamer produces the better results.
The TV is using ARC (and does not support eARC) and is set to output PCM.
I have tried replacing the HDMI connection between the TV and the Wiim Amp Pro with an Optical connection, but this seemed to have the same performance as the HDMI.
I have also tried replacing the Apple TV as the source with a Chromecast, but if anything the quality was slightly worse.
I suppose I’m trying to figure out what could be responsible for the difference I’m hearing.
I imagine one candidate could be the TV, so I’ve been trying to understand what is happening in the audio chain. My understanding is that The Apple TV should be outputting multichannel PCM, and the TV down-mixing it to stereo PCM.
With this in mind, I changed the audio settings in the Apple TV from Auto (LPCM) to Dolby Digital, which sounded much worse, and then to Stereo, which I think may have made some slight improvement to the sound, although this was pretty marginal if any.
So my question now is what could the TV be doing to the signal? I’m suspicious that it is not passing it through unaltered, even though the input and output are both stereo PCM. To add further to this theory, the Wiim app reports the same audio format wether I am listening to output from the TV’s own content, or from the Apple TV. I note that some newer TVs have options such as “Pass-through” as well as PCM, which would imply such a difference also.
Is there anyway I can confirm this theory that the TV is impacting the audio quality, short of getting hold of a different one? I’ve seen devices such as HDMI splitters, but I’m not familiar with these and I’m not sure if they could be useful in troubleshooting this scenario.
I guess there are two theoretical ideal chains - Apple TV outputs multichannel LPCM, a TV passes this through unaltered to Wiim Amp Pro, but I’m not sure if the Wiim Amp Pro can decode this? The other chain would be the Apple TV is set to output Stereo PCM, which is passed through unaltered by the TV to the Wiim Amp Pro, but it seems my TV at least is not exactly doing this. I’m not sure if other TVs are on the market which do allow pass-through of Stereo PCM over ARC?
It would be great to get any opinions on what could be causing this quality difference, and possibly how it could be addressed. If it’s not the TV, is is perhaps a configuration issue, or is the signal path meaningfully different when feeding the Wiim Amp Pro from the Digital inputs vs using the Ethernet source?
As a note, when searching before posting this issue, I have seen one other report of this issue on the forum, albeit with a much newer Samsung TV, below:https://forum.wiimhome.com/threads/samsung-tv.3027/
When using the Wiim Amp Pro as a streamer to play Spotify, the quality is, in my view, excellent.
However, the sound quality is not as good when feeding the Wiim Amp Pro from my TV. It seems slightly veiled by comparison.
In my setup, the source is an Apple TV, plugged into my TV via HDMI. The TV then outputs the audio to the Wiim Amp Pro via HDMI ARC.
The output levels of the two inputs initially did not match, with a measured difference of around 12dB at the same volume setting, but I was able to dial this out using the pre-gain settings in the Wiim app, +10 for the TV and -2 for the Ethernet input.
My testing scenario is comparing Spotify audio, with the same track, at the same level using the Spotify app on the Apple TV, compared to Spotify via the built-in Wiim streamer. In this scenario the built in streamer produces the better results.
The TV is using ARC (and does not support eARC) and is set to output PCM.
I have tried replacing the HDMI connection between the TV and the Wiim Amp Pro with an Optical connection, but this seemed to have the same performance as the HDMI.
I have also tried replacing the Apple TV as the source with a Chromecast, but if anything the quality was slightly worse.
I suppose I’m trying to figure out what could be responsible for the difference I’m hearing.
I imagine one candidate could be the TV, so I’ve been trying to understand what is happening in the audio chain. My understanding is that The Apple TV should be outputting multichannel PCM, and the TV down-mixing it to stereo PCM.
With this in mind, I changed the audio settings in the Apple TV from Auto (LPCM) to Dolby Digital, which sounded much worse, and then to Stereo, which I think may have made some slight improvement to the sound, although this was pretty marginal if any.
So my question now is what could the TV be doing to the signal? I’m suspicious that it is not passing it through unaltered, even though the input and output are both stereo PCM. To add further to this theory, the Wiim app reports the same audio format wether I am listening to output from the TV’s own content, or from the Apple TV. I note that some newer TVs have options such as “Pass-through” as well as PCM, which would imply such a difference also.
Is there anyway I can confirm this theory that the TV is impacting the audio quality, short of getting hold of a different one? I’ve seen devices such as HDMI splitters, but I’m not familiar with these and I’m not sure if they could be useful in troubleshooting this scenario.
I guess there are two theoretical ideal chains - Apple TV outputs multichannel LPCM, a TV passes this through unaltered to Wiim Amp Pro, but I’m not sure if the Wiim Amp Pro can decode this? The other chain would be the Apple TV is set to output Stereo PCM, which is passed through unaltered by the TV to the Wiim Amp Pro, but it seems my TV at least is not exactly doing this. I’m not sure if other TVs are on the market which do allow pass-through of Stereo PCM over ARC?
It would be great to get any opinions on what could be causing this quality difference, and possibly how it could be addressed. If it’s not the TV, is is perhaps a configuration issue, or is the signal path meaningfully different when feeding the Wiim Amp Pro from the Digital inputs vs using the Ethernet source?
As a note, when searching before posting this issue, I have seen one other report of this issue on the forum, albeit with a much newer Samsung TV, below:https://forum.wiimhome.com/threads/samsung-tv.3027/
