[88Sound]

The usual disclaimers first: Because of my lack of experience with state of the art solid state headphone amp's I am far from the ideal reviewer. I have never heard a Headroom amp or a Sugden or anything better than a RA-1 until now. From an engineering standpoint, look, feel, operation, this amp strikes me as incredible. Like that line in the Jerry McGuire movie "you had me at hello". So these are my impressions. I have included the initial list of features available in the manual and on the Grace Website because I have added information (italicized) that was gleaned from my conversation with the 901's designer and founder of the company Michael Grace.

The Grace Design Model 901 Reference Headphone Amplifier, is a product marketed to the Pro Studio and not to the audiophile community at all. The 901 is the only headphone amp I know of that contains all of these features in one unit:

- Balanced XLR analog inputs
- Unbalanced RCA analog inputs
- AES, SPDIF and TOS LINK digital inputs
- High current output amplifier drives 8 Ohm loads easily
- 24 position gold contact stepped metal film resistor level attenuator with .05dB channel matching
- Internal linear power supply
- High current , low noise torroidal power transformer
- No electrolytic capacitors in signal path
- Highest quality metal film resistors
- Ultra low distortion 24 bit DAC accepts sample rates up to 96kHz (this is a Cirrus CS43122 DAC)
- Automatic digital de-emphasis filter
- 10dB gain boost switch for –10 sources
- Fast, musical transimpedance output amplifiers
- Precision instrumentation balanced input amplifiers
- Sealed gold contact relays for input select and gain boost switching

I am using a Pioneer DV-47A DVD/SACD/CD player with the 901 hooked up via analog RCA inputs and digital TOS LINK optical inputs. The 901 allows you to instantly switch between the analog input (utilizing the DAC in your player) and the digital input (utilizing the 901's DAC) from the front panel. The DV-47A also has a second set of analog outputs that I have hooked up to an EarMax Pro.

The 901 pushes about every button I have to push. Small Company, very nice on the phone, when I had technical questions about the 901 I was immediately put on the phone with Michael Grace. Turns out he's an HP-1000 owner & fan, also likes the HD600 and made a point to say the 901 will drive the K1000 to satisfactory if not earsplitting levels. Very customer oriented, 5 year parts and labor warranty that's transferable to any subsequent owner. Build quality......Oh My! Steel chassis, solid faceplate, stepped metal film resistor volume control, switches are sealed gold contact... I am an absolute sucker for great engineering design. Weighs in at nearly 8 lbs., which is quite heavy for a half rack unit.

The switches are absolutely silent. While playing music I can instantly compare the DV-47A and it's DAC, associated settings, and interconnects with the 901's DAC. The sample rate on the 901 is not user selectable (like it is on the ART DI/O); it is determined by a frequency comparator, not by the sample rate bits in the digital data. This ensures that the proper DAC filter settings are used even if there are erroneous sample rate bits in the signal (can't tell that was directly out of the manual can you?). So far it seems that CD's always sync at 44.1 kHz and DVD's always sync at 48 kHz. The digital output from the DV47A is muted for SACD's, Sony has evidently learned nothing from their Beta experience years ago, so for SACD's I must go analog to the 901.

There is a High/Low range button next to the Digital/Analog button that you will need to take note of. The High setting boosts the signal 10 dB. If you are listening at a fairly loud level with the low setting and accidentally push this button you will at least be startled! Try as I may I haven’t damaged anything yet.

In every instance I’ve tried so far I prefer the sound of the 901's DAC to the DV-47A's DAC & interconnect. The 901's DAC sounds more 3D, the soundstage has more depth and the instruments sound more realistic and lively than the DV47A's, I have decent but not fancy interconnects so eliminating those when optically connected to the 901 may also contribute to my preference.

A side benefit of having two analog outputs from your source hooked to two different amps makes comparison between amps easy. The switch can be made in the time it takes to unplug and plug in. When I first got the unit I was frantically plugging in phones to the 901, listening, then plugging into the EMP, back to the 901, press the analog to digital button and back…..It made me crazy, scratch that… more crazy!

I am only going to provide some initial impressions of the sound since I’ve only had the unit for slightly over a week and have selfishly been listening to music with abandon, not taking notes or anything. The sound of the 901 is very detailed but not harsh at all with plenty of power to spare, effortless. The phones I have that benefit most are the Grado 325 & RS1. I had no Idea you could play either of these phones that loud without a hint of distortion, positively frightening. The 901 takes control of whatever you plug into it and would be an excellent tool for evaluating other devices i.e. headphones, DAC's, interconnects etc……

With the W100's & W2002's there are times I prefer the EMP and times I prefer the 901, with the Grado's the nod usually goes to the 901. I had always felt the 325 was a little harsh on vocals, female or male, when compared with my other phones. With the 901 that harshness is gone, the RS1’s however have shown the most improvement. I now believe my poor 325 & RS1 were crying out for more current all the time, I just didn’t know it until now.

It is my opinion that the 901 has met its design goals. As much as I like the EMP it would have no place in a project studio, its pleasing tubey goodness (distortion) could have disastrous results when used to make decisions that would effect the outcome of a CD or DVD. The 901 on the other hand is perfect for this application, showing clearly without comment exactly what it is being fed with authority.

There is very little information currently on the Web about the 901. One snippet that carries some weight is Bob Ludwig (President of Gateway Mastering) after hearing a pre production prototype of the 901 ordered 5 for his facility in Maine. By the way if you have a lot of CD’s and you haven’t heard of Bob Ludwig, you don't read liner notes. I would be curious to know how many thousands of albums this man has mastered.

Here are some updates as of 6-24-02:

The switches on the 901 are not absolutely silent all the time, I sometimes hear a very slight transient when engaging or disengaging the digital/analog, high/low switch, or operating the volume control, still quite acceptable.

So far I can get the 901 to sync at 96kHz with DAD discs (DVD-V) only (thanks to Dusty Chalk for the DAD's info!). I have a Bucky Pizzarelli DVD-A put out by Chesky that on the DVD menu you can select 2 channel 24 bit/96kHz output, the DV47-A displays DVD-A V, but it still only outputs 48kHz to the digital out. In my 901 review I stated that the 901 DAC sounded better to me in all cases, I am now finding that on DVD-A discs I like the DV47A DAC better. Somehow I think the DV47A is artificially crippling the digital out down to 48kHz on DVD-A discs but the internal DAC is operating at 96kHz.

Based on some interconnect education I received at this very site I have changed my digital connection between the DV47A and the 901 from TOS LINK (optical) to Coax.

If you want to take a closer look at the 901:
http://www.gracedesign.com/products/...t_frameset.htm

 

[grinch]

wow, that sounds like a really great piece of equipment. i too am a sucker for great build quality and engineering. thanks for the great list of impressions!

 

[dhwilkin]

Interesting. Could you expand on what material you preferred the 901 to the EMP (w/ the W2002), and for what reasons? How loud is the sound at the lowest setting w/ the W2002? Also, what cables are you using?

 

[JMT]

That is one beautiful amp!!! Nice review too, I moved it upstairs.

 

[Hirsch]

Very nice review, and timely as well. I'm in great need of an amp that can handle a particular pair of power-hungry headphones...

 

[88Sound]

Quote:

originally posted by dhwilkin Could you expand on what material you preferred the 901 to the EMP (w/ the W2002), and for what reasons? How loud is the sound at the lowest setting w/ the W2002? Also, what cables are you using?

You've made me crazy again plugging and unplugging but I surprized myself. I put on Marcus Miller's M2 (M squared) thinking that surely all that bass would trip up the EMP/W2002 combo but it didn't, I prefer this CD with the EMP/W2002. I then tried John Scofield's Uberjam....no contest...the 901 all the way. Uberjam has deep impactful drums that the EMP cannot produce properly even at moderate volume. The 901 sounds better on this even with the DV47A DAC, with the 901 DAC it's awesome.

The lowest setting (first click) you can hear all the music at very low volume, enough to carry on a conversation with closed cans.

Here come the stones....Cables are Acoustic Research (AR) 3 feet RCA/RCA for the EMP & DV47A in analog, and if it matters the fiber cable is AR also.

 

[Calanctus]

88sound, thanks. You note that the RS1s have shown the greatest improvement with this amp. When driven by the 901, how would you compare the sound of your RS1, your W100s and your W2002s?

 

[Anders]

Very interesting amp and review. Maybee we should look more into pro audio. Have noticed that a Swedish company that mostly sells pro audio also has some of the most interesting audiophile components. Waiting for the follow up, but take the time it needs.

 

[88Sound]

Quote:

originally posted by calanctus You note that the RS1s have shown the greatest improvement with this amp. When driven by the 901, how would you compare the sound of your RS1, your W100s and your W2002s?

That's a tough question, a long answer, and involves a lot of personal opinion. The sound of these phones must also include the amps EMP & 901 in this case.

The W100's have a colored sound that I think works very well with some material....old jazz....audiophile recordings of female vocal, ala Chesky, etc. These phones sound great with that material and the RA-1, If you change the amp to an EMP you add a class A triode tube amplified sound.....everyone who's heard this type of amp knows what I'm talking about....if you haven't I don't know how to put it into words but it's magic. The 'magic' of this type of tube amplification is by definition distortion....the incoming signal is changed and in this case the results are glorious. So for the W100's I prefer them mostly with the EMP. I would never use the W100 or EMP for mixing or mastering a CD but they have their place and I love them none the less.

The W2002's are much less colored than the W100's, they have a cleaner more accurate sound and also a bit more impact. These phones sound great in both the EMP & 901 and are material dependent on what amp they sound best with.....see my earlier surprize when trying to answer dhwilken.

The RS1's are pretty neutral with a warm coloration, but they are also the most current hungry of the three phones, The RS1's sound good with the EMP but on some material the EMP cannot produce the current the RS1's need which results in soft, fuzzy bass up to and including a more audible distortion. Here's where the 901 comes in. The 901 has current in abundance and has raised the level on the RS1 & 325 to a place that was not possible with my previous amps. Just got through listening to Uberjam with the 901/RS1 combination at near a live level and am speechless. Deep impactful drums and bass, no matter what cocaphony is going on you can hear cymbol decays to the very end. It's this type of control that is necessary in the studio so you can make decisions based on fact and not the colorations of your equipment. Incidentally you would probably not use any of these phones in the studio, you need something accurate and boring, the Grado's are anything but boring. Something like an AKG240 or along those lines.

 

[JMT]

Nice avatar.

 

[Toddathan]

Thanks, 88sound--

Any thoughts on the performance of the DAC?

I'm sure that the DAC accounts for a good portion of the price, and if it's particularly good, then this could be a real bargain for someone looking to upgrade their headphone amp and DAC.

Also, you said the designer indicated that the the 901 can drive the AKG K1000's with no problem. So, does it have XLR outputs or speaker terminals to connect the K1000's?

 

[88Sound]

Quote:

originally posted by JMT Nice avatar.

So, you recognize one of your babies....The mighty penguin...field champ!
Quote:

originally posted by toddathan Any thoughts on the performance of the DAC?

The only thing I know about this DAC is I love the way it sounds. If you go to my original review I have posted the model # in the list of features, you can go to the Cirrus website (formerly Crystal) and look at all the Specs for that model #.

The only outputs on the 901 are two standard sized headphone jacks. If the K1000's have something other than that you would need an adapter.

 

[grinch]

88sound:

you say that cds sync at 44.1khz and dvdds sync at 48khz when using the grace's dac.. i wonder, because my friend's dvd player has a setup menu where you can change the output of the digital connections. this particular one could be set to 96khz. i am not sure how exactly it works (for cds and dvds or just dvds, etc.), because i wasn't able to try it out with my own dac. i am interested to see if this makes any difference for you though.. care to try and find it? it's usually only accessable from the "setup" button on the remote control. (like where you would set your player to be in 16x9 or whatever mode..)

 

[Tomcat]

Quote:

High current output amplifier drives 8 Ohm loads easily

88Sound,
so, basically, you have bought yourself a power amp for driving your high efficiency horn speakers? Impressive. If it can drive K1000s, I bet it'll easily control any headphone there is.

Quote:

The 'magic' of this type of tube amplification is by definition distortion....the incoming signal is changed and in this case the results are glorious.

I am not so sure that inaccuracy can be a reason for better sound. I'm with Duke Ellington and JMT: If it sounds good, it is good. To me, musicality and accuracy are one and the same thing.

I'd love to read a more detailed comparison of the W2002 and the W100 in the Headphones Forum. Will you post one once you have all your new sonic impressions sorted out? You can say what you want: joelongwood syndrome rocks. I am glad you have it.

 

[88Sound]

grinch,

The first thing I tried was going through all the screens on the DV47A to enable it to output 96kHz, but I still have yet to run across a DVD that will cause the 901 to sync at this rate.
Quote:

originally posted by Tomcat I am not so sure that inaccuracy can be a reason for better sound. I'm with Duke Ellington and JMT: If it sounds good, it is good. To me, musicality and accuracy are one and the same thing. I'd love to read a more detailed comparison of the W2002 and the W100 in the Headphones Forum. Will you post one once you have all your new sonic impressions sorted out?

Although the word 'distortion' usually carries a negative conotation my definition is any change to a signal other than amplitude. Distortion and inaccuracy although sometimes the same are not always.

I purposely distort signals all the time when I'm doing sound, EQ's, sonic maximizers, gates, compressors, limiters, de-essers, etc., etc.,. These distortions make the sound better, a lot better. Ah, you say live sound is not the same as a CD! Well here's a senario..... You record an artist in the studio or live event, there are certain ambient sounds and other things present at the event that are lost during the recording, including changes in phase relationships. When you play the finished recording back it sounds good but not exactly as the original event. There are several different things you can run this CD through that will restore some of the things lost during the recording process. The devices that do this restoration are adding distortion in relation to the signal they are given even if the final outcome is more like the original event.

I completely agree when listening to music for pleasure that if it sounds good it is good. I said the EMP sounds glorious.....that's not very close to bad. If however you are a professional in charge of making changes to sound on a recording so it sounds its best on all equipment you must have an completely accurate sound, otherwise your decisions will based on colorations your equipment is adding and not the actual recording.

It might be semantics but to me musicality and accuracy as it relates to a recording are completely different. I have a lot of great music that for various reasons, usually age, have a lot of problems when held up to the light of complete accuracy. The W100/EMP combination for instance transform these less than perfect recordings into breathtaking musical events, and many of them were recorded nearly fifty years ago. These colorations I do not like on everything but they sound great on a lot of things. There are also several new recordings that have problems when listening with accurate headphones....Jane Monheit, and the latest Diana Krall CD's have distortions and overloads in various places. For pleasure I prefer listening to these with the W100/EMP combo because it is more forgiving...more musical. I wish however that the people who released these CD's had heard the problems and corrected them before release.

That's my story and I'm sticking to it!

As far as the W100/W2002 comparison.....do I have to?