The possible benefits of using an AVR for playing Pure Stereo?

[corElement]

Long post : Beware

In the process of converting my 5.1 setup to stereo I've been experimenting with my Jamo e875 floorstanders, Jamo AVR-693 and Asus Xonar D2X. The objective being to find the right balance of settings for stereo.

Oddly I've found that when I set everything to stereo on the soundcard+avr the sound quality is inferior compared to the sound quality of non-upscaled stereo content fed to the front towers directly via DTS connect.

Basically what I'm saying is that

- Stereo content in full stereo settings on soundcard and avr
- Stereo content upscaled to 5.1 on soundcard and channeled to avr through DTS

Both of these are sounding inferior to against stereo being played without up-scaling through a DTS signal to just the front two towers.

I never really understood what people made a fuss over about pure stereo but this has really given me a taste of what pure stereo can be like but what's screwing with my head is that it's NOT A STEREO SIGNAL, it's a DTS signal.

Whenever I play outside of DTS there's a lot of electrical noise and the sound is very harsh but through DTS it's beautiful and silent.

So a few things came to mind:

1. A digital signal cleaned up a lot of electrical distortion - why?
2. Stereo content that's upscaled to 5.1 really sucks in comparison to it's non-upscaled form - Whats the cause behind this?
3. Can an integrated stereo amp actually suppress electrical noise like a digital signal can?
4. Why are AVR's looked down upon for playing stereo content?
5. Are there integrated stereo amplifiers which accept Digital inputs like Dolby/DTS?
6. Am I really missing out on anything with what I have against a purely integrated stereo amplifier?
7. If the speakers by nature are excellent in mids and highs but weak in lows, can an integrated amp make any difference? (the amplifier is not weak on bass because ive heard it on another pair of speakers and their bass was quite good so the speakers are definitely weak, I've tried adjusting by 3db on equalizer but it's definitely still weak on bass...I dont mind really considering theres 0 hum and the midrange is pretty insanely hypnotic on the e875's )

Would like to know the thoughts of experts.

Below are the specifications of my equipment for a better understanding:
-----------------------------------------------

JAMO AVR-693

Specifications
Power output:
Front ..............................................................2x120W
Surround ........................................................2x120W
Center ............................................................... 120W
Center surround................................................ 120W
Total harmonic distortion ..................................0.08%
Frequency response.......... 2020,000Hz, +1dB/-3dB

JAMO e875 towers

System Type 3 Way Bassreflex
Woofer (mm/in) 2 x 140 / 5
Midrange (mm/in) 140 / 5
Tweeter (mm/in) 25 / 1
Power (W, long/short term) 150 / 220
Sensitivity (dB, 2.8V/1m) 89
Frequency Range (Hz) 32 - 20.000
Impedance (Ohm) 6
Weight (kg/lb) 19,3/42,55
Overall dimensions (mm/in, HxWxD) 1011x175x361/39,8x6,89x14,21
Finishes Cherry, Black Ash
Inputs Gold plated bi-wiring screw terminals

Asus Xonar d2x


Audio Performance

- Output Signal-to-Noise Ratio (A-Weighted): 118 dB
- Input Signal-to-Noise Ratio (A-Weighted): 118 dB
- Output THD+N at 1kHz: 0.0004% (-108dB)
- Input THD+N at 1kHz: 0.0004% (-108dB)
- Frequency Response (-3dB, 24-bit/96kHz input): <10Hz to 46kHz (for all channels)
- Frequency Response (-3dB, 24-bit/192kHz input): <10Hz to 90kHz (for all channels)
- Output/Input Full-Scale Voltage: 2 Vrms (5.65 Vp-p)
- Sample Rate Conversion Quality: Almost lossless, high-fidelity floating-point filters, which has:
-140dB THD+N (typical value for 44.1K->48KHz, 24bit)
-145dB Dynamic Range (typical value for 44.1K->48KHz, 24bit)

Main Chipset

- 4-bit D-A Converter of Digital Sources: Burr-Brown PCM1796 *4 (123dB SNR, Max. 192kHz/24bit)
- 24-bit A-D Converter for Analog Inputs: Cirrus-Logic CS5381* 1 (120dB SNR, Max. 192kHz/24bit)

Sample Rate and Resolution

- Analog Playback Sample Rate and Resolution: 44.1K/48K/96K/192KHz @ 16/24bit
- Analog Recording Sample Rate and Resolution: 44.1K/48K/96K/192KHz @ 16/24bit
- S/PDIF Digital Output: 44.1K/48K/96K/192KHz @ 16/24bit ?Dolby Digital, DTS, WMA-Pro
- S/PDIF Digital Input: 44.1K/48K/96K/192KHz @ 16/24bit
- ASIO 2.0 Driver Support: 44.1K/48K/96K/192KHz @ 16/24bit

 

[anm]

hey have you tried taking 2 channel digital PCM out from your sound card to AVR?
It could also be the analog "in" of your AVR being a weak link?

Harman Kardon has "stereo receivers" that take 2 channel digital signal and use their internal DACs.

 

[marsilians]

1. A digital signal cleaned up a lot of electrical distortion - why?

First of all you have to understand that the channel paths for stereo and DTS are entirely different on your sound card and AVR. I suspect this to be an issue with the sound card because anyway you play a stereo signal, you are hearing noise. I dont believe the AVR analogue is the issue since the DTS signal plays well through it when downscaled to 2 channels.

A naive question, are you playing a DTS cd by any chance? If so, you will hear noise if its not processed as such. Have you tried a regular CD with stereo output?

2. Stereo content that's upscaled to 5.1 really sucks in comparison to it's non-upscaled form - Whats the cause behind this?

What format are you upscaling this to? Also could you clarify what sucks means? Is it loss in volume or addition noise or anything else? generally, one does the opposite of downscaling multichannel to stereo. Also the difference in volume (normally perceived as quality) between multichannel and stereo is big since all the channels (say 5.1) are pushed through 2 so a lot more frequencies are bundled together. A true 5.1 has some frequencies split across the various channels resulting in low volume output through the front L/R speaker pair.

3. Can an integrated stereo amp actually suppress electrical noise like a digital signal can?

No, though you can suppress noise in multiple other ways before the signal reaches the amp. but again I dont think thats the issue here.

4. Why are AVR's looked down upon for playing stereo content?

Not all AVRs are bad. some older generation ones and a few new generation ones produced terrible stereo output. By nature AVRs were built to reproduce multichannel and the resulting parts and circuits when compared to a stereo receiver or integrated are generally of lower quality.

Denon's 16xx series, Yamaha 6xx series and Onkyo 5xx series have improved stereo playback in the low to mid market sections. Traditionally good AVRs with good stereo output in higher end segment are Anthem, Marantz, Meridian, Nuforce, Lexicon, Rotel, ...

5. Are there integrated stereo amplifiers which accept Digital inputs like Dolby/DTS?

This is generally not the case as the integrated amps are meant for pure 2 channel vs. an AVR that is multichannel and Dolby/DTS are multichannel signals. As far as I know only Bel Canto, Peachtree Audio and couple of Onkyo integrated have optical inputs.

6. Am I really missing out on anything with what I have against a purely integrated stereo amplifier?

Best way is to try and see it. borrow one from a friend. If you were in my city, I would have let you borrow mine but again be careful as the price differentials could be big so ensure you make like-like comparisons.

7. If the speakers by nature are excellent in mids and highs but weak in lows, can an integrated amp make any difference? (the amplifier is not weak on bass because ive heard it on another pair of speakers and their bass was quite good so the speakers are definitely weak, I've tried adjusting by 3db on equalizer but it's definitely still weak on bass...I dont mind really considering theres 0 hum and the midrange is pretty insanely hypnotic on the e875's )

See my response to 6.