[imackler]

There used to be daps that had a separate jack for fixed line out (Ibasso DX50, DX90, Fiio X3, X5, etc.) Most newer daps now have a variable line out, meaning that the volume adjusts the line out digitally, even if it's not amped (as much as I understand it.) It is almost always the SE 3.5mm headphone jack as well.

I feel like the fixed is somehow a more "pure" signal. I always liked with those daps that increasing the volume didn't affect the line out.

But does it really matter? Is the source degraded when processed through a variable line out? Are current daps compromising? Or is variable line out as good, or in any ways preferred?

Thanks for any help on this!

 

[ProtegeManiac]

There used to be daps that had a separate jack for fixed line out (Ibasso DX50, DX90, Fiio X3, X5, etc.) Most newer daps now have a variable line out, meaning that the volume adjusts the line out digitally, even if it's not amped (as much as I understand it.) It is almost always the SE 3.5mm headphone jack as well.

I feel like the fixed is somehow a more "pure" signal. I always liked with those daps that increasing the volume didn't affect the line out.

But does it really matter? Is the source degraded when processed through a variable line out? Are current daps compromising? Or is variable line out as good, or in any ways preferred?

Thanks for any help on this!

This is primarily because the DACs used aren't topologically purely just DAC chips anymore that require an line output stage and then a headphone amplifier stage after that, where the line out is split from the line stage to skip the amp output stage. Now they're using the DAC chips that can also be used on mass market devices (which is weird, because other than Samsung and now dead LG phones, who'd even get these?) that have the DAC, output stage, and headphone driver stage (albeit a weak one) in the same chip.

Think of it like an APU, except instead of Bulldozer APUs this is more like modern M1/M1X/M1 Pro or Ryzen 6000 with RDNA chips.

AFAIK, even the iPod had something like these but like Bulldozer, and triggering line out with the 30-pin just maxes out the output but runs it through some caps (which is what gets upgraded in the 4g iMod), and that works just fine, although the max voltage is 1.2V. On modern DAPs with higher output though they don't just max out the volume because it will actually exceed the Redbook standard 2V, so what it does is set it to a predetermined output level that will equal 1.8V to 2V depending on how clean their implementation of a given integrated DAC chip is. For example my AP80's line out locks it at about 80% output and it's still lower noise and higher voltage than my Ibasso D-Zero's line out (1.2V), so I can use it as a DAP and as a music server with my desktop amp (controlled by my phone) once I get home.

 

[imackler]

Thank you so much for your help! It sounds like maybe I'm holding on too much about the way things used to be with the dedicated fixed line out port. Going forward, it doesn't sound like I should be worried about sound quality more from a variable line out than a fixed line out, right? Sounds like that has become industry standard?

Do any daps standout for having excellent line out, even if its variable? Or, in general, is it that whatever I read in a review about the dac implementation should be true of the line out? I've got a good portable amp I'm quite happy with so really looking for something to use as a line out mostly (though if it has a low noise floor I could use it with sensitive iems too). I guess I'd like as cheap as possible, as long as it has a great line out. A plus would be if I could do Apple Music on it, but I'm ok too if it only has a quality dac/line out.

What would maybe you suggest as the best...
1) Cheap as possible option that has a micro sd slot and great dac/line out. I'm willing to sacrifice on pretty much everything on this option except sound quality via the line out...
2) A less cheap option that has a micro sd, runs Apple Music in bit-perfect, has a great dac/line out. I'd probably look for a bigger screen on this one since my old fingers can navigate a folder system, but hate using streaming apps on a small device...

BTW, are there any phones that have a good line out? That would be so cool...

 

[ProtegeManiac]

Thank you so much for your help! It sounds like maybe I'm holding on too much about the way things used to be with the dedicated fixed line out port. Going forward, it doesn't sound like I should be worried about sound quality more from a variable line out than a fixed line out, right?

To be honest if they actually got rid of the bugs in the Fiio X5III and X7 I'd have picked that over the AP80. Or if I had $1,000 and wasn't about to move, I'd have replaced my now buggy Android with a real hi-fi server just so I can easily scroll content with a phone app UI and as a bonus I'd have 2V line out.

But for what I can get at this time it's not really bugging me.

Sounds like that has become industry standard?

For DAPs? I guess, since it simplifies the board lay out, and makes them slimmer.

Do any daps standout for having excellent line out, even if its variable?

I'm not sure what you mean...when you set it as line out it won't be variable as the manufacturer will preset it to a 2V output level (or max if the chip outputs less than that). My AP80's volume knob doesn't work when on LO mode. It's just that it's the same circuit, but again, it will lock the output level.

Or, in general, is it that whatever I read in a review about the dac implementation should be true of the line out? I've got a good portable amp I'm quite happy with so really looking for something to use as a line out mostly (though if it has a low noise floor I could use it with sensitive iems too). I guess I'd like as cheap as possible, as long as it has a great line out. A plus would be if I could do Apple Music on it, but I'm ok too if it only has a quality dac/line out.

If you check out specs there might be cases where the noise rating can be higher than the headphone out mode but even then that would be if they tested the line out mode as it is, ie, set the output to 2V, but the headphone out might have been measured at very low output level with a 300ohm load for example (which at that level might be too low for actual listening). I can't recall one that actually rated this way, but if anything can make it look like modern shared PO/LO hardware makes the LO look bad in any way, this is one way to do it.

A plus would be if I could do Apple Music on it, but I'm ok too if it only has a quality dac/line out.

If it has a full Android mode with PlayStore access I guess that's the safest way to bet on it, but might as well check each player's page and see if they have it installed by the manufacturer or downloadable as easy launch side loads onto their limited OS mode.

What would maybe you suggest as the best...
1) Cheap as possible option that has a micro sd slot and great dac/line out. I'm willing to sacrifice on pretty much everything on this option except sound quality via the line out...

Hidisz AP80? That's what I got holding me over for portable and home use until my move is final so I don't have to haul too much stuff on a plane (more so when I'm hauling cats too).

2) A less cheap option that has a micro sd, runs Apple Music in bit-perfect, has a great dac/line out. I'd probably look for a bigger screen on this one since my old fingers can navigate a folder system, but hate using streaming apps on a small device...

Fiio M11 maybe.

BTW, are there any phones that have a good line out? That would be so cool...

GSMArena says they all measure the same but cranking up a phone to the same level as the DAC in my Meier makes for a noticeably noisy system over using a 1.2V DAC (charging current off) or the built in DAC in the same Meier amp.

Granted, that can also be because the amp has such a low noise floor, so adding any will be noticeable if you're comparing back to back.

Plus one problem there is phones don't really have a line out mode, much less a separate line out. Let alone a 3.5mm output jack...is there even any with one these days? That's also one reason why I have a DAP (again). It's either a dongle or TWS IEMs, but the DAP has line out so I can use it at home.