Zu Omen Defs and Ice Amps?

Anyone have the opportunity to audition a pair of Zu Omen Definitions and a Class D or Ice Amp? The Zu's obviously don't need a lot of power so I'm thinking one of these newer digital amps might be a good fit. If so, please share the make/model of amp and your impressions. So far, I'm considering the King Rex, Trends, Dayton, and Topping amps but I'm sure I've left a few out that might be contenders. Thanks in advance.
I just had a Onkyo 9555 on a pair of Definitions while i waited for a new preamp.

Bad move. Class D and Zus are a TERRIBLE match.

Tube or Mac--that would be my decision.
They're a bad fit because the Zu FRD sounds best with an amp with a relatively low damping factor. That's what it's designed for. Bass will be overly damped (dry, thin) with any kind of digital or switching amp.
Whats with all these Class D amps. My friends bring them over to my house and say look it weighs almost nothing and it will produce some crazy amount of power like 500 watts per channel. Then they will proceed that it should keep up with my Pass Labs X350.5. The class D does not come close with the most important part the sound quality. Next the Class D will make your ears bleed in the process. The flat tinny sound must be in style these days. All aside my friend has pair of ZU audio Omen Definitions and they sound extremely good with his collection of tube amps; 1) Modified Jolida 502B, 2)Manley Stingray 3)Cary 300B Integrated 4) Modified Dynaco ST 70 with a Dodd Audio Buffer Preamp. All those amps do a great job and hold a class of their own and still kill Class D as for sound quality. Buy decent tube amp and those ZU Omens will sing the way they were designed.
>>06-08-11: Glory
All D amps suck<<

That, dear friends, displays not only stupidity but a complete lack of experience.

Audio morons are alive and well in Florida.
I don`t agree that "all" class D amps suck, but they are not ideal for all speaker types(no amp is). I do believe that for Zu speakers in general they`re at their best with good quality low-moderate power tube amps(SET,OTL orpush-pull). Also one of the First Watt amps should work well.
The Class D amps I've heard do indeed suck, but then I wasn't crazy about the Zu Omens either, which a friend owned for about a week. I imagine that the Zus and the Class D amps I've heard would be a marriage made in hell. Audiofeil probably sells others.
Not to take away from this thread's intended question, but to defend Class D amps: if you haven't heard the Spectron Musician III Mk2, please don't rationalize that all Class D amps suck.

I chose mine after comparing it to my Karan KA I-180, Burmester 036 and Pass XA30.5.

Audiofeil - I agree. I use small class D Rowland 102 amp with Hyperion HPS-938 speakers (90dB sensitivity). Sound has presence and resolution but also softness and fullness. Bass is punchy and powerful. Instruments sound very natural with great harmonic structure. There are even many better class D amps these days, so it is hard to understand how anybody can toss general statements like that.

Class D amps are very revealing, I'm sure you agree, ruthlessly unmasking any system deficiencies - otherwise it would be hard to understand why others describe similar amp as "ear bleeding", "dry" "thin" etc. while I hear just the opposite - smooth, clean and full sounding.

"The Zu's obviously don't need a lot of power so I'm thinking one of these newer digital amps might be a good fit."

Texas42 - Digital amps are "a lot of power". I often see such statements relating to lower power tube amps and high sensitivity speakers. More power won't hurt but there is a risk of overdamping, as Paul suggested - need to check synergy. It worked for me in spite of 90dB rating.
Indeed I do sell a line of Class D amps. But that is not germane to my criticism of the Florida butthead.

If you believe all suck, perhaps a move to Florida is in your best interest.

Inexperience and ignorance reign supreme there. You'd fit right in.
I will throw out a general statement about Class D is mid fi at best. I have listened to way too many Class D amps and to two that have been mentioned in this thread and they have big power but they do not deliver the quality. The problem is that manufacturing good old fashioned power has gotten very expensive here in the USA for the average US citizen. To build a strong Class A or AB amp you need to dissipate a lot of heat and that requires lots of machined aluminum metal, that is very expensive. It was not a problem until the dollar sank and our economy went south. The reason that high efficiency speakers are popular these days is that you can use high quality old fashioned lower power amps and get better sound than what you get from a 1000Watts of negative feedback switching power supply power amp. The manufactures are also struggling to make stuff people can afford. Under normal economic conditions I they would be a place for Class D but it would not be in high end sound systems. I am not saying that Class D is a bad technology what I am saying is that it needs to improve. I remember when I got my first CD player and I had a first pressing of The Police Synchronicity on Vinyl and bought the CD. What a let down the CD was. No one believed me that the vinyl record blew away the CD. My friends thought I was crazy. What was scary is that I had a Yamaha CDX 1100U CD player and a very very cheap Technics belt drive turntable with a cheap Ortofon p mount cartridge that sounded better then the summmer job's wages I saved to buy that Yamaha CD player.

You're absolutely right! My Spectron is only mid-fi at best!

The question is, what does that make Karan, Burmester and Pass, since I chose it over them?

Why don't you e-mail Wayne Donnelly at "Enjoy The Music" and tell him that. After all, he chose it over the very expensive VTL mono-blocks.

Then, go and e-mail all of the reviewers who've given the Spectron very nice reviews that their hearing is obviously impaired.

Mid-Fi my A--! I'm glad that I've never been to your stereo shop, who knows what you consider as high-end.

"of negative feedback switching power supply power amp."

It makes me suspicious of "negative placebo effect" when somebody has already opinion on switching in general.
Switching supplies are the same thing as class D amps. In addition to efficiency they have line and load regulation that linear power supplies are lacking. Latest $13k Rowland 625 - class A/B amp uses switching power supplies.

Noise from switching supplies is easier to clean because of higher frequency - that's why Rowland uses them in preamps where efficiency is of secondary importance.

Linear power supplies, if you thing about it, are really switchers operating at 120Hz poluting with 120Hz strong narrow current spikes of high harmonic content. This high harmonic content in addition to very high rms/average value ratio calls for oversized transformers. On the other hand ferrite transformer at 100kHz can carry 10x more power than toroidal 60Hz transformer of the same size. I would speculate that switching power supply, now days designed with zero voltage/zero current switching, got bad rap from extremely crude switching supplies in computers.

Why then linear supplies are still so popular? - for two reasons:
1. mistrust in new technologies (that was just expressed)creates demand for old technology (if it's heavy it has to be good).
2. any idiot can design linear supply - not so with the switcher (very complicated).

As for negative feedback - there is very little of it in class D since ouput is very linear by definition and output impedance is very low (inherent since output Mosfets always connect speaker to low impedances (GND and VCC). Iceamps have two feedbacks. One controls the timing of free running oscillator while the other is traditional analog one with perhaps only 20-30dB control.

So if anybody is objecting to class D technology or SMPS I'd like to add that delta-sigma converters, SACD and DSD operates on the same principle (Pulse Width Modulation)
For the record:
It is correct that very powerful amplifier, like our Musician III, can be rather poor match for the high sensitivity speakers. This why each and every Musician III leaving factory (sold new or after upgarde, repair etc) is tested on 98 dB sensitivity single woofer speakers and not on difficult to drive ones.

Many believe, I suspect, that all class D amplfiers have, and I quote: "....negative feedback switching power supply power amp " It is not so. Our Musician III, Mark Levisnon No.53 and few other class D amplfifiers use traditional "heavy" linear ones (Mark Levinson single monoblock weights, I believe, 170 lbs!).

It is not to say that there are no excellent switching power supplies (which can be used with class A,B,C,D,E etc amplifiers. One is that by Jeff Rowland (fully reguilated with PFC) and another, I know of is ours own which we use exclusively in our pro audio products (also fully regulated with PFC).

Moreover, I believe and I could be wrong that recent NuForce Ref 18 and Bel Canto 1000 Mk2 amplifiers use essentially older ICE Power based output stage(s) but improved the B&O switching power supplies by addition of extra capactitors and as I read people like the improvments but I probably should not go into subjective sonic opinions.

Simon - some Rowland amps (like 301) based also on standard Icepower modules with built in SMPS use Power Factor Correction supply in addition that converts 120Hz charging spikes common to 120Hz rectification to smooth full cycle mains current. In addition PFC converts 110VAC to almost 400VDC making for much better operation of Icepower's SMPS(lower losses).
Audiofeil, do you have problems reading? I said the Class D amps I HEARD sucked. Two of them. Both pretty favorably reviewed.

"If you believe all suck ..." I never said that. And I'm neither inexperienced nor ignorant. Stop being a jerk.
Kijanski and Krellman,
Why be so defensive? It`s a free market with many choices of amplifiers to choose among. If you prefer class D amps that`s a personal preference, nothing more or less. Others have tried them and found better sound elsewhere(no crime).

The fact that a particular reviewer likes the Spectron amp, OK, well he likes it. Some reviewers prefer SET,OTL,P-P tube or solid state, that does`nt add or subtract credibility at all. You guys bought what suits your taste, but it is`nt for everyone.
A good Ice Power amp would be a sound choice in the SS amp camp, but frankly, I suspect there are many SS and tube amps that can also do a top notch job with those in that I believe the rap is they are pretty efficient and easy to drive.

The consumer market Zu appears to target will probably lean more towards tube amps. IcePower amps appeal to a different camp of consumers I suspect.

The amp I am familiar with that I would like to hear most with those is the Tube Audio Design 125 Hibachi monblocks, which is a SS amp designed to sound more like a traditional tube amp.
"Two of them" - My all thumbs to you but please promise that it will stay 2 (won't turn into 1).
I have to wonder what people are listening to or thinking when they label Class D or Icepower amps as "mid-fi". They must either be hearing something different than what I hear, have not heard a good setup, or perhaps just prefer a different flavor of sound. That is fine, but prefering a certain flavor does not mean that other established flavors are inferior.
Charles1dad - It is not being defensive but rather irritated with "All D amps suck" statements.

If you read my first post, I stated that I chose the Spectron over three other well known SS amps. Personal preference to be sure, but I never bad-mouthed any amp or any person. Anyone on Audiogon who regularly reads Glory's posts and ads expects that kind of remark from Gary as being, just Gary. Tomorrow he may say that Class D amps are the best in the world.

If you read my second post, like Kijanki, I'm more irritated that someone, especially a dealer, has the audacity to tell Audiogon members that their system components are mid-fi, whether it is or isn't by somebody's definition.

If I hear a system, but think that mine is better, why would I risk hurting the audiophile's feelings bashing it? To flat out say what George (TheSoundHouse) said is just arrogant and demeaning.

kijanski and Krell man,
I understand your objections more clearly now. High End audio is hopelessly subjective and we all just like what we like. I love SET amps but realize they`re not everyone`s cup of tea.
06-09-11: Audiofeil wrote :

Indeed I do sell a line of Class D amps. But that is not germane to my criticism of the Florida butthead.
If you believe all suck, perhaps a move to Florida is in your best interest.

Inexperience and ignorance reign supreme there. You'd fit right in.

Audio morons are alive and well in Florida.


Audiofeil Bidniz must be booming .... LOL :):):):):):)

They do not all suck as I missed your smart ass remarks lately. Kind of knew the D amp statement would bring you out of the cess pool for some kind/ thoughtful writing.

Good to you are your cranky self and have not lost your DH status.

D amps are great in the right system. Hope that picks up your D amp sales Billy.
In the context of the OP thoughts about Zu speakers and D amps , all D amps suck.


After all I did to try to make peace with you on these forums after all your gay comments about me which is untrue I do declare you are a true Dick Head.

What is the damping factor on your amp?

Zu says the damping factor must not go over 200.

It's 500:1. What that means and why Zu says that it shouldn't be more than 200:1, I don't have a clue.

I know nothing of electronics workings and measurements.

DF does not make much difference once it is higher than 100 since inductor in series with the woofer has typical 0.08 ohm making residual DF of 100. Changing amp's DF from 200 to 1000 will make only about 36% difference in overall DF (possibly less if you count cables connectors etc).
If you are worried about 'excess damping factor', toss a power resistor in series with the speaker. That'll lower the damping factor! And 'simulate' a current source amp, using SS. Carver did it and so did Pass (experimentally)

The Zu enclosure / driver combo is probably designed to be critically damped, with a Q of about .71 This may not react well to hi damping factor amps.
The lower DF of tubes makes it sound.....right......

PS: The inductor in my panels has a DCR of 0.4ohms. An inductor of .08 ohms would be pretty small.
All class D amps do not suck.I agree with Audiofeil about the "All class D amps
suck comment"Makes about as much sense as people who say ,all fords ,or
chevys suck! And I live in Fla.
0.4 ohm is pretty high limiting DF to 20.

Here is an example of good inductor for the woofer:
"The lower DF of tubes makes it sound.....right......"

Probably an accurate statement.

High damping Class D amps may still sound good or better in some cases but I suspect these are in the minority. I would likley try it since I own good Class D amps but likely end up not going that way with the Zu's myself.

I picked up the TAD 125s as a complement to my Class D amps for my other system where I currently use more tube friendly speakers and may well end up trying others as well there down the road. The TAD has a lot of tube attributes however the bass is very well damped and controlled in comparison to many tube amp systems I have heard. The sound is more like what to me are the better sounding tube amp systems I have heard where it is not easy to determine a tube amp is being used by listening. A very high end VAC/Magico system I have heard comes to mind. I suspect only bigger and more expensive tube amps can drive those really well.
The total resistivity of the woofer panel / inductor is over 4 ohms....The ICE amp I use will yield a pretty high DF.

I'd be careful changing inductor Resistance since it will cause a change in driver balance and effect crossover point.

My DIY design is within 5% of the original inductor, aircore and 14ga. wire....Therefore NO current limiting and NO saturation.
The stock coil? 16ga. iron core......
I don't know about the Omen Defs, but Zu specifically recommends two different
class d amps on their website...

I used one of the two recommendations (Panasonic XR-25 and it was meh) but I did use the Virtue TWO.2 and it was not bad at all for the superflys.
I think everyone one of you audiophiles need to goto this link listed below and read from page 7 on about Virtue M5001. I have these mono amps and have upgraded the capacitors/tube/fuses on the Dodd Tube buffer. I change the sonicaps to euro oil caps, change the tubes to CV4035/M8137 and changed out the fuses to hiFi tunning fuses. With these upgrades, these amps play as good as my Lamm M1.2 ref. So all you Class D haters, goto this link and scroll down to page 7 and read. http://www.affordableaudio.org/aa2010-05.pdf
I don`t sense any hate for classD amps in this thread at all. People have heard or tried some and just prefer something else. If you`ve found an amp you love and it happens to be classD then feel fortunate, we all have different taste and priorities.
Charles, if you read the info on page seven on that link that was in my last message, you will see that my whole intention was exactly what you describe to me. Good Day!

You sold your Lamm amps for a D amp that is a no show on the map? LOL

Wait till you wake up and find out what you did, you are going to be very angry with yourself.
Glory, If you heard these amps since i have done the mods, you wouldn't have posted your last message. Besides, it is all about taste and priorities and i have found these amps after the mods to be a step above my Lamm M1.2 ref. Good Day!
When I first got my (standard) Omens, I used them with one of the new Bel Canto C5i integrated amps. I believe this is an ICE amp rated at 120wpc at 4 ohms. They sounded ok, but I always felt the bass sounded thin with that amp. Some weeks later, I completed a Bottlehead S.E.X. amp, which is a 2.5wpc SET amp. Lo and behold the Omens had a whole different sound with the little Bottlehead amp. Low frequencies especially sounded alot fuller and richer.

I spoke with the folks at Bottlehead and the consensus was the lower damping factor of the tube amp was producing more apparent bass. For whatever reason, the little SET amp just sounds better on the Omens than the ICE amp.
Yes, another of many examples that illustrate the mandatory proper matching of amplifier and speaker. A well made SET amp can sound disarmingly natural and "real" sounding with the correct speaker. With an inappropriate speaker these amps will predictably disappoint.
I realize I am late to this thread, but I recently purchased a pair of Omen Defs and are running them with a Wyred DAC-2 directly to Wyred SX-500 mono amps. Sound is absolutely spectacular (to my ears and my tastes). There are so many variables to system synergy -- associated equipment, and the most important aspect that is often overlooked, the room itself. I have the Omen Defs in an upstairs loft that is 15' x 35' x 8' -- these speakers like room to breathe. The final placement of the speakers was somewhat farther apart than other speakers I have had. They throw a massive sound stage, and with the Wyred gear, they are extremely fast, dynamic and smooth -- not edgy or shrill at all. I can't really comment on the lower octave as my room has a 'hole' in the 40 - 50 Hz range. I have a subwoofer to augment from 50 Hz down (have had to use that for every speaker I have had in this room).
Afraid to stir the pot BUT I'm looking to possibly purchase a ZU ht system based on the omen def and need a good multichannel amp. Any suggestions? I know most above dislike the class d amps but wondered about the wyred 4 sound units that seem to be getting good reviews.

I had an HT system consisting of 2 pairs of Omen Defs and an Omen center, all powered by Wyred 4 Sound amps (3 SX-1000 monos for the front 3, pair of SX-500s for the rear). It sounded fantastic (everyone that came by to hear was floored by the sound, and many who 'debunked' class D were surprised to learn that's what they were listening to). I have now upgraded to Definition MKiii speakers in the front, and have moved up to a pair of mAMP mono amps powering them. Again, they sound fantastic in 2 channel (several people were very surprised to learn they preferred the Wyred setup - mAMPS and STP/SE -- over a highly touted tube integrated), and just as good for HT. I would not hesitate to recommend the Wyred amps for an Omen Def theater system.
I am on my forth Pioneer Elite Class D Receiver. The first three; SC-07, SC-05 then a SC-35 all fell apart as in the jacks in back shorted out in less than 2 years. Pioneer will not do a thing. They claim the wires i.e. cables were too heavy. I was using Monster and Transparent cables. The forth one was given to me by Best Buy for free. They felt sorry for me. I got a Sc-67. It is not an "ICE" but still class D. Ice is a trademark of B and O. My advise is stay away from Pioneer "ICE" Products. Most imporant; Pioneer outright lies about their power ratings.
I do not have ZU. I hear that that they are very good. I went with Tekton Pendragons. Very Happy. Too power Our type of speakers check out Shelbourne and Outlaw. Same price but made in USA and they are separate Amplifier and Processor! Good Hunting!