Review: ZERO 24 BIT/192KHz DAC/Headphone Amp/Pre-Amp - Page 106

Yeh i'll let you know. Theres a clock upgrade too that i may consider. It will be in a few weeks if i get one, i need to get paid first! ha ha.

They do look amazing though, hope they sound the same!

I didn't test how hot they became when I use my gear for the whole evening because there were no problems. I think it will be in the temp range where op-amp is designed to be functional.

I'll do some more testing tonight :rs2smile:

@penchum:
Didn't you write in your review that the LT1028 can't be used with the DAC as they are not unity gain stable?
From where did you get this information?

I powered on my gear and there is again background hiss and some kind of whining sound when I turn the volume all the way up. The noises are quieter than yesterday.

Have to listen more and see if it goes away again.

Well I've got mine running for the second day continuously - let you know how that goes when I get back from work today

Can't believe this thread's still runnning BTW been away for a bit after slightly losing interest in my Zero, having not been able to find an opamp combo to hands-down beat my other equipment.. but a long-delayed browndog and pair of AD797s arrived yesterday so I started playing again (didn't like the 797s all that much, so figured I'd give those LT1028s a go and what a pleasant surprise!)

So far best combo I had was LME49720 in both DAC and headamp, had 2 metal/2 plastic, so had a metal one in the DAC. Now with the LT1028 in the DAC board I've put my two metal LMEs into the headamp.

This combo's a keeper for now, but there's a distinct loss of resolution compared to 'LMEs all round' - think I'll order a third metal LME and maybe some (metal?) 627s which I haven't tried yet.. I know this little machine's got it in it to be absolutely amazing, as I've heard most of what I like with the all-LME combo, just it was lacking bass (that I've now heard with the 1028, at the expense of resolution - argh! ) and had a weird gap in the mids - so the search for the holy grail continues

That discrete opamp thing looks kind of tempting, esp. what with money-back guarantee... (anyone got any experience with it or others? does it really beat the 627 like the eBay description claims?)

Oh, I also put the stock BB2604 back in just for kicks - surprisingly nice compared to my initial impressions (though not a keeper - perhaps just an indication of what the more expensive 627 might sound like - and seems all very promising at that )

Did the same with my ceramic DY2000 - and it's still not to my taste Anyone want to do a swap for another opamp they might have knocking about surplus to requirements?

Hehe - yeah/thanks, though I can see where this slippery slope is going - it's going to take time and probably a decent amount of money before I settle on a combo I like.. Suppose once I do I can sell off all the surplus, and hey it's something to do/keep-me-of-the-streets so to speak (and who knows, doing it this way you learn a thing or two + could well stave off the usual upgrade-itis compared with simply buying a $400-800 pre-built unit)

Bit stuck for ideas on what else to try in the headamp board meanwhile, what with the limited space (e.g. can't try 'OP627s-all-round') unless of course anyone knows of some sort of flexible wire adapter available for this sort of thing, to just have the socket somewhere else in the case?

Overall though, I'm thinking that's got to be the way to go - experiment with the same op-amp in all three sockets to get an idea of it's characteristics in isolation then combine with something else, or settle for something cheaper if it makes little difference for example...

It's going to get pretty expensive, pretty quickly, with things like 6x OPA627 though (and what do you do when you start thinking things like "hey I wonder if I can hear the difference with the TO-99 metal can one?"!!) - if only there were a way to do this in a shop and just buy what you want at the end much like at a high-end hifi shop

I guess the alternative would be to experiment with a high-end headphone amp you're familar with, plugged in to the pre-amp out, settle on a DAC opamp choice, then try to get the internal hedamp sounding as similar as possible with further fiddling

Anyway hopefully at some point or another we'll have figured out 3-4 'kick-ass opamp combos' to put in the first post and we can save new people a whole lot of money and leg-work

Right that's all good stuff/thanks - in that case I'll be ordering at least two metal 627s when Mr Wu at diykits is back from holiday (seems to be by far the cheapest place for those), and I'll look into those adaptors seeing as I've only got two right now/would have needed at least one more anyway at some point (and the type I've got does fit into the left side of the board if you carefully bend the caps out of the way, at least on my unit).

Also I'll have to have another go with my 1364s - didn't like them at all the first time round but now I'm beginning to appreciate that this whole burn-in thing does actually make a real noticeable difference!

Something I noticed: if you keep the OPA2604 in the DAC, the LT1057s, LM4562s, LT1361s, LT1364s in the headamp section are not heating. Even the LT1469 is just warm.
As soon as you put one that gets hot in the dac section, the LT1361, TL1364 and LT1469 are getting hot in the headamp.
Oscillations with high bandwith opamps??
The components in the Low pass filter of the DAC may not be sweetable for all opamps.
I will try to draw the schematic around the opamp DAC to see what I can get.

I got an email reply from Cimarron Tech about the 627 on adaptor. They have them listed on site at https://www.cimarrontechnology.com/i...ATS&Category=6

Prices on that page are for a single 627 on 2 types of adaptors. Thoughts on this anyone?

is there a way i can use line out from my iriver and connect to the coax? it only has a mini headphone jack