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Originally Posted by devast /img/forum/go_quote.gif
Always use bitperfect imo. The pcm1793 does oversampling anyway, upsampling is a lossy procedure. Also, the aune can not handle anything over 24bit and 96khz over spdif, and 24/48 over usb, so probably your windows mixer just downsamples it before sending it to the unit.... meaning you do two unnecessary steps that each modify the sound.
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Ah, yes you're right about the USB thanks, thought that was a bit strange. Now i've compared them through my speakers it's obvious, the reduction in soundstage and air is very apparant, but i still prefer the upsampling through headphones where those losses aren't noticable but the reduction in glare is welcome.
I really need to get a laptop with a digital out.
According to the seller the DAC handles 24/192 though.
I've had the Aune a couple of months now so thought it was time to play with the op-amps, and had an OPA2107 and a Browndog single-to-dual adapter drop through the letter box.
First i swapped the OPA2134 with the 2107 as several people have suggested and hated the sound. I can see why some people prefer as it seems to tighten everything up and give better bass but to my ears everything sounded slow and sluggish, like the life had been sucked out of it. I tend to judge in terms of realism and balance than overall bass and treble, and this chip isn't for me.
So i put the 2134 back and nipped up to Maplins to get an NE5532 and 3 5534s. I swapped the OPA2604 for the NE5532 and heard a vast improvement, there was much more body and life to the music and more depth in to the soundstage. I then swapped the NE5532 for the Browndog with 5534s and noticed a slight further improvement.
The i put the 2604 back in so the Aune was back to standard and listened for a bit, nice sound but the NEs are a definate improvement with no drawbacks.
I then left the 2604 in and swapped the 2134 for the NE5532 and noticed a similar improvement in the body and soundstage, but this time with a very light distortion in loud passages, as if the amp was clipping. I then swapped the 2604 with the NE5534s (so i'm running the 5532 in the DAC and 5534s in the headphone amp) and this distortion became more apparant, and annoying.
Right, so i listen again to the original 2604 in the DAC and the 5532 in the amp, and the swap the 2604 for the amp's 2134 and felt the sound deteriorated. So for me at this stage the original 2604 sounds best in the DAC.
The 5534s sound best in the headphone amp but i'm curious to try the output bypass mod (remove pin 6 of the mono op-amp and short pin 5-6 of the socket), so i bend up pin 6 on one of the 5534s and carefully bend pin 5 across to fit pin 6's socket, just to see if it works, put the op-amp back in and... there's sound so it works. I have a listen to a couple of tracks i know and then swap the modded 5534 to the other channel and listen to the same tracks, just to see if i can get an impression of how the sound changes. I do this a couple of times and notice what i think is a slight improvement in the body of the sound from the modded 5534 but will need to verify this by modding both channels and comparing non-modded 5534s. However, i also notice a 'pop' on the modded channel when i switch the amp off so will need to sort this out if i want to go with the output bypass, and as i'm planning on listening to AD744s before i make any decisions there's no point me modding at this stage.
So i'm done testing for now and have decided on th 2604 and 5534s. I take the modded 5534 out of the Browndog and replace it with spare 5534 and... there's smoke! I obviously wasn't paying attention because i put the spare 5534 in the wrong way round... d'oh!
Question is, what else have i damaged? Can't see any obvious signs of damage to the board or components so chuck the 5532 back in (the right way round!!) and... *bang*! Something in the 5532 explodes and cracks the op amp.
What an idiot!
The DAC still works but now i'm without a headphone amp. Hopefully i'll work out what the damaged components are but it might already be time for a new headphone amp.
