[barongearmu]

 
I don't think these are actually the same filters that are employed by the m9XX.  I think the m9XX uses custom versions, primarily for anti-aliasing and anti-modulation distortion control more than to actually change the sound.  Unfortunately the bifrost 4490 is the only other amp I know of that uses this chip and it doesn't seem to allow you to use the filters at all, so it's hard to find a point of comparison.  My reason for thinking this is that Grace actually goes out of their way on a couple of the filters to say the effect shouldn't be directly audible, unlike how they're described by AKM as changing the sound.  

Plus, there's four of one, and five of the other. I'd think if they were just exposing the underlying filter it would match up. Unless maybe the "traditional" filter by akm isn't a mode, but just a picture for comparison? Need to go look up some spec sheets.

 

[lvince95]

  I have the portable CEntrance DACport HD, which I believe uses the same chip.
However I was convinced (by others) that implementation would be so different as to make it impossible to tell which mode was in use by CEntrance.

Yeah, it's widely known implementation of DAC chips are far more important than the DAC chip itself but I didn't know it would affect filters too But it makes me wonder, if each DAC will be utilizing the DAC chip in a different way, will any of the DAC's actually have the original filters listed on the AKM site? Or I guess there is a way to leave the filters untouched, I have no idea though.

 

[fjrabon]

  I have the portable CEntrance DACport HD, which I believe uses the same chip.
However I was convinced (by others) that implementation would be so different as to make it impossible to tell which mode was in use by CEntrance.

yes, it seems like most manufacturers who use this chip just pick one and then customize it.  Grace interestingly allowed you to pick from custom implementations of 4 of the 5 available.  At the very least, the filters as implemented by the m9XX are WAAAAAYYYYY more subtle than the AKM site makes them out to be.  I can maybe hear some as closer and further away in presentation, if I'm trying really hard, at which point I'm probably doing more mental convincing than critical listening.  The only thing I've ever definitely noticed with them is the claimed (by grace) anti-aliasing effects and intermodulation effects (especially when the grace is used in front of a tube amp, the intermodulation effect seems to be much more noticeable on tubes, as I suppose the ringing that's auditorily invisible can cause issues in tubes).  

 

[barongearmu]

Looking at the data sheet, I only see four filters that I would say match up with the grace definitions. The differences between them, are incredibly tiny. Thousandths of a db.

 

[fjrabon]

  Looking at the data sheet, I only see four filters that I would say match up with the grace definitions. The differences between them, are incredibly tiny. Thousandths of a db.

yeah, I think that is why Grace chose not to focus on the directly noticeable sound signature effects, and instead focused on how they impact aliasing and downstream modulation distortions.  I think it's also possible, if not likely, that Grace toned the filters down into something more subtle sound wise, and instead chose to focus on using them for fixing problems rather than shaping the sound.

 

[barongearmu]

 
yeah, I think that is why Grace chose not to focus on the directly noticeable sound signature effects, and instead focused on how they impact aliasing and downstream modulation distortions.  I think it's also possible, if not likely, that Grace toned the filters down into something more subtle sound wise, and instead chose to focus on using them for fixing problems rather than shaping the sound.

Further in the datasheet, it describes how external filters can also be integrated, or used in combination with the the internal filters. Looks like a lot of different things could be done here. Seeing some of these values, I appreciate the engineering that must have gone into not only the DAC chip itself, but using it, must be very finicky and challenging. Props to AKM, props to Grace.

 

[fjrabon]

 
Further in the datasheet, it describes how external filters can also be integrated, or used in combination with the the internal filters. Looks like a lot of different things could be done here. Seeing some of these values, I appreciate the engineering that must have gone into not only the DAC chip itself, but using it, must be very finicky and challenging. Props to AKM, props to Grace.

yeah, I talked to Michael Grace about this for a bit, and he said that most people realize that the AKM4490 is the best delta sigma chip, period, end of story, but that few manufacturers use it, because it's kind of complicated to work with.  Many prefer a very simple plug and play solution with their chips, instead of having to work with it to implement at its best.  So, no surprise that the main three that do use it: Grace, Schiit and CEntrance, are amongst the most experienced delta sigma DAC builders.  

 

[Magick Man]

I've definitely found a pairing that isn't very good, the Beyer T70 is far too "lean" and strident sounding with the m9XX. As a standalone DAC going to my old NAD IA, or a Valhalla 2, it's excellent, but definitely not with the m9XX's internal amp. In fact, I think this is probably the most drastic difference switching between amps that I've ever heard. :blink:

 

[EinZweiDrei]

i too run m9xx through a valhalla 2 for my 300ohms senns.
but for my k701 and 400i i run them straight into the m9xx.

 

[sheldaze]

400i straight from m9XX is bliss, but K7XX sounds better to me m9XX > Vali 2 with stock tubes.

 

[Psalmanazar]

Grace is using the different modes of the AKM chip. F2 is the "Original sound" one and the best filter and is comparable to the Schiits in the size of the sound stage but lower fidelity as instrumental separation is worse due to the Grace's bass bloom (tape sped, pitch-shifted drum tracks sound not particularly pitch shifted) and lack of resolution of treble transients (triangle and snare 8th and 16th notes are blurred). F1 is the "powerful sound" and doesn't really work as described with overly compressed masters: it messes with what panning information they have and presents the high frequency nastiness from being overly compressed (not clipping) in your face while the ringing causes other problems; everything sounds like "headphones" with F1. I didn't bother checking the minimum phase ones and still need to check the pass through of the M9XX into other things to see if the bloom and treble issues are in the DAC or amp portions of the unit.

 

[Magick Man]

With an external amp I really like F4, but I really don't care for F1 at all, while it gives the illusion that you're hearing more detail, it adds an edge that makes long term listening annoying/fatiguing.

 

[fjrabon]

Grace is using the different modes of the AKM chip. F2 is the "Original sound" one and the best filter and is comparable to the Schiits in the size of the sound stage but lower fidelity as instrumental separation is worse due to the Grace's bass bloom (tape sped, pitch-shifted drum tracks sound not particularly pitch shifted) and lack of resolution of treble transients (triangle and snare 8th and 16th notes are blurred). F1 is the "powerful sound" and doesn't really work as described with overly compressed masters: it messes with what panning information they have and presents the high frequency nastiness from being overly compressed (not clipping) in your face while the ringing causes other problems; everything sounds like "headphones" with F1. I didn't bother checking the minimum phase ones and still need to check the pass through of the M9XX into other things to see if the bloom and treble issues are in the DAC or amp portions of the unit.

So you're A/Bing the bifrost 4490 and the m9XX through the same external amp?

 

[olek]

I've definitely found a pairing that isn't very good, the Beyer T70 is far too "lean" and strident sounding with the m9XX. As a standalone DAC going to my old NAD IA, or a Valhalla 2, it's excellent, but definitely not with the m9XX's internal amp. In fact, I think this is probably the most drastic difference switching between amps that I've ever heard.

 
That is interesting. Your observation mirrors my comment here from about a month? ago. The funny thing is that over time either my m9xx, T70 or my ears (or all 3) 'broke-in', and I do not mind T70 out of m9xx amp anymore. I do not use that pairing often simply because Crack/Speedball is making T70 sound a good grade better across the board, but I would not say that T70 + m9xx is bad pairing anymore. Maybe I am listening to different music those days? Maybe I learned to never push T70 to higher volume limits? Dunno, but my opinion slowly changed a bit.
 
I did more of A/B testing (not blind!) of DACMini and m9xx dac section... and m9xx sound is growing on me. Listening to Sarasate Carmen Fantasy through DACMini, Itzhak Perlman's violin sounds a bit like a ... gypsy's violin, 'rough and unruly'. With m9xx it sounds like a sweet and precise seduction instrument, and I like that. Oh wait, Itzhak style is known to be a bit more on the 'force' side.... hmm... I do not know which dac is more truthful, but I find myself preferring m9xx for intricate work more and more, with DACMini maybe having better synergy with pop/rock music.

 

[Psalmanazar]

So you're A/Bing the bifrost 4490 and the m9XX through the same external amp?

Schiit Modi 2 Uber + Magni 2 Uber vs the Grace M9XX. They pretty much both sound very similar due to the AKM chips with their own flaws (bloom and treble transient issues on the M9XX, steely but unexaggerated in volume treble on the Modi 2 U)
 
I don't have a Bifrost and I still need to feed the Grace into the Magni and maybe an old receiver or two to see if it's the amp or the DAC with the bloom.