[IEMCrazy]

As I wait for the eventual arrival of my D5ks I'm considering what to do amp-wise for it.   My first attempt will be using my Lyr.  Jason already informed me he feels it's too noisy for them given their sensitivity, but it's worth a try first, since that's the simplest and highest quality option (and is "free" since I already have it).  But if I find the noise floor too high, I'll need to pick something else. 
 
I have a Fiio E11, but I'd prever a desktop solution since the E11 is my portable unit and keeping the battery charged and having too small a volume knob for my listening station would get annoying.   E9 is the next obvious choice at a good price.  But I've heard the opamp that comes with it is less than ideal.  Is there any step-up amp from E9 that anyone can recommend for the Denons?  Asgard would have been an option, but with the heat I can't stack it under Lyr, and being sensitive to treble fatigue, I suspect the pairing would be a bit too bright.  I wouldn't pay more than the price of the Asgard for an amp for a single set of cans.
 
Mostly I'm looking for a warmer-than-brighter amp with a large-ish volume pot and good quality for such a great headphone to shine without the noise floor being too visible (if Lyr works ok, though, I probably won't need a different amp.)

 

[formula1]

I know a few. Budget? Tubes or SS? 

 

[IEMCrazy]

 
Quote:

I know a few. Budget? Tubes or SS? 

 
Under $250, since if I were going up to that level I'd probably just get Asgard as a compliment to Lyr, and I don't want to spend a fortune on a single headphone's amp.  My first impulse is to say tube, but with low impedance I'm not sure tubes are ideal for Denons.  The warmth is appealing though.  So probably SS, or hybrid.  But if there's a tube that works well at that range, I'm open.

 

[formula1]

On your budget i know the Audioengine D1, works really good with low impedance headphones. Another option is the O2 amp. 

 

[IEMCrazy]

 
Quote:

On your budget i know the Audioengine D1, works really good with low impedance headphones. Another option is the O2 amp. 

 
The D1 seems like it's probably a waste since I don't need a DAC (if paying $x for an amp + dac, how much of the money is going to the DAC?)  But the O2 is promising when pre-assembled!  That may be a good idea and still costs quite a bit less than Asgard.  Appearance/ease of setup/no-cables running everywhere, Asgard would have been ideal if I could have stacked them....but I don't think putting anything on top of that heat monster would be a good idea.  Especially not another amp!  It sounds quite a bit better than E9, which I've always had doubts about, and costs roughly the same to boot.
 
I'll have to see how Lyr goes first though.  If I'm happy with it, a single-amp solution would still be idea. Having different amps for different cans just gets messy!

 

[shamrock134]

I find the Lyr to be too noisy with all of my "easy to drive" cans like the D5K, D7K and Edition 8. Only suitable for high impedance and orthos IMO.

 

[haejuk]

I have D2ks, and the amping requirements are exactly the same as your D5ks (same drivers).  I had a Fiio E9 and liked it, but had the itch to upgrade and came across some interesting options.  Many people like the Little Dot I+ (a tube hybrid amp) with their Denons.  I have this with upgraded soviet military tubes (similar to Voshkods) and I really like the sound I hear.  This one is $150 new, shipped from China. 
 
I also picked up a Meier Corda Arietta (discontinued) off the used forum for $150 shipped.  This one sounds amazingly clean and controlled compared to the Little Dot I+, but somehow sounds a little weaker.  In the end, I am keeping both amps and using both of them for my D2ks.  As a bonus, the Arietta has an output impedance of 0 and works better than any other amp I currently own with IEMs (I assume you have some because of your id).
 
They both have quite different sounds and I don't want to give either one up.  Both of them are dead silent with no music playing at my listening volumes.  You can't go wrong with either of them for the price, both of them sound better than my old E9.  You might get lucky if you put up a want ad in the used forums for either one.
 
I am working on building an O2 to see how that sounds with Denons.  I haven't heard it yet, but have heard positive comments about the pairing.

 

[IEMCrazy]

...and formula1 wins the cookie! 
 
I ended up ordering an assembled O2 from JDS.   I was curious about NwAvGuy's design, especially since it measures so well, and considering his holy crusade against tubes and coloration (which I don't agree with.) But at least I'll know what "perfect measurement" sounds like.  It's been compared very well to the headphone amp in the DAC1 (but with much lower output impedance.)  More importantly, it actually fits where I need it to fit next to my Bifrost/Lyr.  (In a fun twist, much to NwAvGuy's dismay, I'll be plugging it into a Schiit Bifrost though...

)
 
Its cheap, fits where I need it, and supposedly measures well.  Fits the bill for a single headphone's amp, and a backup (versus the Headroom I vastly dislike the sound of) SS for when tubes bring Lyr down.  I just wish it had the jacks in the rear and a 1/4 HP jack....other than that, it's a slick little box for the money.
 
The E11 works fairly well with the Denons, but the volume control is atrocious, too much gain ramp up on the knob.  I also feel that at very low volume the E11 has insufficient voltage swing (despite the low impedance) and the headphones sound very thin, but there's a huge jump in volume with the pair a little further where the cans really come alive but are a little too loud for my liking.  It makes me miss the smooth pot of better amps....and the assembled O2 seems to have a good pot.  The E11 also gets overwhelmed and tends to mud things a little compared to, say, the Lyr.  Unfortunately Lyr works (with even a bigger sweep of the volume pot!) but the tubes are indeed too noisy for it and I get a lot of on and off screech/whine through it.

 

[Rope]

I push my MD5000s with the Lyr/Bifrost combo and have zero noise issues.  Not the slightest hint of hum, however, that was not the case before the Bifrost addition.

 

[IEMCrazy]

 
Quote:

I push my MD5000s with the Lyr/Bifrost combo and have zero noise issues.  Not the slightest hint of hum, however, that was not the case before the Bifrost addition.

 
MD5000?  I'm guessing one of the advantages of that uber-cable and the Futuretech plug is maybe an increased impedance/resistance which would lower the noise floor considerably.   Just a guess, though.
 
I have two Lyrs, both running the GE tubes, and both generate considerable screech/hiss/whine over the Denons.  These are tubes that run very, very clean with HD650, K702, HE-400.  Jason also confirmed that Lyr is just too noisy for Denons.  So it's got to be an  impedance difference with the mods on MD5000 versus stock D5000.  Alternately Malveaux told me he didn't notice a noise floor with the combination except for very quiet passages and only if the volume was turned up to relatively higher volume listening. 
 
It's possible I'm just sensitive to tube whine.  I had a very faint periodic whine with the one tube on HE-400 & K702 and it was driving me absolutely crazy.  I thought it was power line noise or noise on the volume pot and I'd have to live with it since a tube change didn't solve it.  I swapped the tubes and the noise changed channels.  It turns out both sets of tubes had the same kind of whine in the same position tube.  After that I replaced just the whining tube and it's been fine ever since. 
 
But both tubes reveal lots of whine on the super low impedance D5k.

 

[Rope]

 
Quote:

 
 
MD5000?  I'm guessing one of the advantages of that uber-cable and the Futuretech plug is maybe an increased impedance/resistance which would lower the noise floor considerably.   Just a guess, though.
 
I have two Lyrs, both running the GE tubes, and both generate considerable screech/hiss/whine over the Denons.  These are tubes that run very, very clean with HD650, K702, HE-400.  Jason also confirmed that Lyr is just too noisy for Denons.  So it's got to be an  impedance difference with the mods on MD5000 versus stock D5000.  Alternately Malveaux told me he didn't notice a noise floor with the combination except for very quiet passages and only if the volume was turned up to relatively higher volume listening. 
 
It's possible I'm just sensitive to tube whine.  I had a very faint periodic whine with the one tube on HE-400 & K702 and it was driving me absolutely crazy.  I thought it was power line noise or noise on the volume pot and I'd have to live with it since a tube change didn't solve it.  I swapped the tubes and the noise changed channels.  It turns out both sets of tubes had the same kind of whine in the same position tube.  After that I replaced just the whining tube and it's been fine ever since. 
 
But both tubes reveal lots of whine on the super low impedance D5k.

 
 I'm not going to get into the cable debate, but there's no cable mod on my MD-5000.  Strictly damping and ear cushion mods (see Mark L Mod), this mod cleans up the flabby bottom end and upper bass region. Low microphonic tubes (PCC88 7DJ8 Lorenz).  Before adding Bifrost, I had to keep the volume on the Lyr at, or right around 10:00, or the hum was unbearable.  I cannot explain the absence of hum.
 
Chain:
WMA Lossless >Squeezebox Touch (ethernet rounter connection) > Toslink > Bifrost > BBE 422 > Lyr > MD 5000 (stock cable) > HiFiMan 500 (stock cable) > AKG K701 (stock cable).
 
Perhaps I should roll-in some Mullards, GE, or such and see if the hum returns.  What I can add is, every tube has it own sound signature and characteristics, some highly microphonic and will sing their own song at certain frequencies (junk).  Any tube is microphonic if execited by outside source, such as tapping the tube lightly with a pencil eraser,  they'll ring like a bell.

 

[IEMCrazy]

 
Quote:

 
 
 I'm not going to get into the cable debate, but there's no cable mod on my MD-5000.  Strictly damping and ear cushion mods (see Mark L Mod), this mod cleans up the flabby bottom end and upper bass region. Low microphonic tubes (PCC88 7DJ8 Lorenz).  Before adding Bifrost, I had to keep the volume on the Lyr at, or right around 10:00, or the hum was unbearable.  I cannot explain the absence of hum.
 
Chain:
WMA Lossless >Squeezebox Touch (ethernet rounter connection) > Toslink > Bifrost > BBE 422 > Lyr > MD 5000 (stock cable) > HiFiMan 500 (stock cable) > AKG K701 (stock cable).
 
Perhaps I should roll-in some Mullards, GE, or such and see if the hum returns.  What I can add is, every tube has it own sound signature and characteristics, some highly microphonic and will sing their own song at certain frequencies (junk).  Any tube is microphonic if execited by outside source, such as tapping the tube lightly with a pencil eraser,  they'll ring like a bell.

 
Oh, I thought the "MD" desgination implied the full overhaul (cushions, damping, cups, and that ultra funky cable.)   Interesting about the hum.  My source is somehow very interesting, and your post has confirmed for me if my source is odd, or if my previous source was the odd one.  On my two previous sources (into Bifrost), iPod Touch LOD & Pure i20 iPod Dock, I kept the volume of Lyr at around 9:00 at all times.  When I changed to Squeezebox Touch, I had to drop the volume by almost half, down to 7:00-8:00.  Considering we're talking digital coax into Bifrost, and the same Bifrost generating the line level into Lyr, there's something going on in the digital domain for one or the other.  Either SBT is applying digital gain boost, or the Pure and iPod were applying digital gain cut.  I don't know how SBT could be boosting though since it even has a mode for fixed 100% gain explicitly for audiophiles that don't want digital gain manipulation.  You're using SBT though as well....Toslink vs. Coax may be the difference, but I find that hard to believe.  Do you have SBT set to "Fixed 100% Volume" in the setup or are you applying digital volume control or ReplayGain?  Or is the BBE 422 doing any serious cutting?
 
Also which tubes are you using on the Lyr, you mentioned rolling GE, and I'm using 6BZ7....but if you're using the JJ's they should both be around the same vgain. And I've had those lovely ultra microphonic tubes...the Japanese 6BZ7 models are nasty microphonic.  Within 200 hours they generally ring like a gong if your headphone cable touches the side of the Lyr housing.  WIthin 300 hours they start ringing like a gong if you don't.   (They were replaced with the US ones, and when I pointed out to Jason that they even make a Japanese version, he was amazed and pulled all the remaining stock of them....apparently a few boxes slipped into their shipments.)  The USA ones are much, MUCH more quiet.  I love the tubes.....with headpones above 30ohm anyway.

 
 
 
If I were to crank Lyr to 10:00 I'd likely blow my headphones AND my ears with it, with the exception of one or two very quiet classical recordings I have around.
 
However, that doesn't involve the hiss/noise/whines from the tubes into the Denons, which happens with the volume at 0, or up at 11:00 without fail....it's the pure noise at the jack into such a low impedance.  No microphonics on these tubes, but  am using the stock GE's

 

[IEMCrazy]

For anyone interested in the results of this, even though it's a now defunct headphone, I will say I greatly dislike Fiio E11 with the D5k (and by virtue, D2k and D7k.)  While the Lyr was unsuitable due to the sheer noise floor of the 10x gain amp, the E11 is less noisy but still has a periodic but frequent "rustling leaves" EMI sound, especially during quiet parts.  While this may be the result of the Wifi antenna on the squeezebox in semi-close proximity, the point is the thing is not adequately shielded for normal operation, and the noise floor is elevated as a result.  Some of the sound may be DC leakage off the caps as well.  I found the battery depleted after sitting idle for 2 months.  A genuine Nokia battery should not deplete like that.  Something in the amp was pulling juice while it was supposed to be off, and I'm sure if that's the case some of that leakage happens while it's on and ends up in the output too.  On higher impedance phones (including my IEMs) that's not an issue, but the Denons pick it up.
 
Even on low gain, the cheap volume pot doesn't do it well, and volume control is minimal and fickle. A bump too far in either direction is either too loud or too soft.  I miss the nice smooth Alps on my Lyr
 
Finally the Fiio does something to the tonal balance.  It's not bad by any means, but it seems to color the sound to be bass-heavy.  Or just isn't supplying high enough current.  The bass ends up BIG...it extends low, but it's also disconnected from the rest of the spectrum and bloats out into a very big "bass boost" feeling sound.  This is with the bass boost circuit supposedly off. While it has a great subwoofer sound if you like flabby bloated bass, it sounds like a 14" sub being used for music that is calibrated higher than it ought to be in a 2.1 setup.  
 
I thought this a characteristic of the D5k at large until just now I plugged it into my Denon 2310ci AVR (if there's no synergy there, where would there be?)  The 2310ci has a pretty good headphone amp for an AVR.  I find it almost identical to my Headroom Micro (Desktop) for HD650 (though I'm not find of the Micro for 650.) and I believe is one of the handful of AVRs that tie the headphone jack into the main L/R A amplifier section instead of gluing on a cheap opamp for the headphones.  So it's getting genuinely good quality amplification on here.  (-44.0db is a fun volume setting for their own brand headphones

)
 
In the meantime, after learning how the E11 mangles the FR, it has me considering an Altoids tin CMOY for my IEMs and ditching the E11.
 
 
Other than the absence of any noise floor the one thing that jumps out at me (or rather, doesn't jump out at me) is the bass.  It's now linearly integrated into the rest of the FR response and doesn't stand out on its own as though it's an uncalibrated sub.  It sounds like a properly setup 2.1 now.
 
My AVR doesn't exactly sit close to my listening area, so it won't serve as the permanent amp, and I'm awaiting my O2 next week for that task (I wish it were the upcoming desktop O2 with 1/4" & RCA jacks...but oh well, 1/8 will have to do. But the Denon amp proved what these Denon cans are capable of.  And a very smoothly integrated FR curve and low, low (but well integrated bass) is part of the response so long as the amp is appropriate.
 
I still like my HE-400 on Lyr better than the D5k on the Denon, but I like them almost equally and they present the music in two very different ways, I love the pairing.

 

[Rope]

The noise floor issue you're experiencing is the 100% gain setting, SBT digital domain.  Switch that to variable, then do some experimenting with various digital volume settings, while leaving the analog volume set around 11/12:00.

 

[IEMCrazy]

 
Quote:

The noise floor issue you're experiencing is the 100% gain setting, SBT digital domain.  Switch that to variable, then do some experimenting with various digital volume settings, while leaving the analog volume set around 11/12:00.

 
The trouble with changing down the gain settings on the SBT is that introduces digital gain reduction.   Moreover, while I generally dislike bitrate conversion, 16bit->16bit processing is VERY bad since it effectively reduces the bitrate to 14 or 15 real bit depth depending on level of gain applied, which introduces quantization errors above the noise floor.  So although bitrate conversion is bad, gain manipulation and DSP processing, if it must be done at all, should involve bitrate conversion to (just to keep it standardized) 24bit to keep the quantization below the floor.
 
Since the Bifrost relay clicks when changing bitrates (as do most AVRs), and there is no click between when I have digital gain set on versus 100% on the SBT, it seems safe to assume that it's 16->16 bit bit with the processing.  Artifacts above the noise floor are annoying.
 
Thus a new lower gain, lower noise amp

 
Still, I'll play with some of the digital gain, just to see if indeed the noise goes away.  I suspect it won't since I did rotate the dial quite far (probably up to 11:00 or so) without signal being played, and the noise was pretty constant all the way around, and wasn't tied to the position of the volume pot at all.  The noise seems unrelated to attenuation.