KEF 104/2, new NAD and Rotel amplifier impressions

[twodeko]

I'm currently driving a pair of refurbished KEF 104/2s with a NAD C370 and decided to see how other amplifiers would sound. Each setup was driven with a Topping D30 DAC and not built-in DACs.

I purchased a NAD C368 (80 WPC, hybrid class D amplifier) integrated and found that the low frequency response was similar to the NAD C370 in that it was present, but didn't have much oomph. The upper mid-range and high end sounds far more clear and bright with the C368 compared to the C370, but not fatiguing with these KEFs. This was very evident with dynamic guitar (i.e. Rodrigo y Gabriela).

I also demo'ed a Rotel A14 (80 WPC, class A/B) integrated to see if the lack of a powerful low end was due to the amplifiers or speakers, and surprisingly found a much smoother and present low end and mid-range compared to both NAD amps. However, the high end isn't as bright which may be a drawback with the KEFs. The more powerful low end was evident with electronic music (i.e. James Blake) and drum-heavy classic rock.

Are these listening impressions consistent with what you'd expect for vintage KEF reference speakers? I've been running the NAD C368 for over a month now so perhaps my ears have gotten used to how clear/bright this amp is, but neither NAD amplifiers seem to drive the KEF woofers as well as the Rotel.

 

[Lou G]

I have been running my KEF 104/2s with an Acurus A200 (200 WPC). This is a wonderful combination; deep tight bass (can actually rattle the windows with certain tracks), a rich full midrange and a smooth high end that is not bright at all. The KEFs have superb detail and imaging with a large soundstage that fills my entire listening room. They also have the deepest 3d soundstage that I have ever heard. Absolutely no fatigue, I can listen to them all day.

 

[twodeko]

Thanks for the feedback!

Agreed with your comments, but my main curiosity is whether the audible differences in amps makes sense based on others' experience. It seems odd to me that the NAD amplifiers would lack deep bass, even the high WPC C370, or perhaps the Rotel frequency response isn't completely flat.

 

[Lou G]

I can't comment on the NAD or Rotel amps, I have never used them. I can say that the 104/2s do require some power (current) to open them up and get the best bass response. I initially ran my 104/2s with a British Onix A-120 integrated amp (100 WPC). A very sweet sounding amp and I was very pleased with the sound. Than I tried the Acurus A200 (200 WPC) and immediately noticed a deeper more pronounced bass response with more impact. The mid range and upper frequencies were very similar with both amps. I moved the Onix to my KEF Calindas where they are a perfect match.

 

[Ross6860]

I have been running my KEF 104/2s with an Acurus A200 (200 WPC). This is a wonderful combination; deep tight bass (can actually rattle the windows with certain tracks), a rich full midrange and a smooth high end that is not bright at all. The KEFs have superb detail and imaging with a large soundstage that fills my entire listening room. They also have the deepest 3d soundstage that I have ever heard. Absolutely no fatigue, I can listen to them all day.

I would agree.

I have more detailed speakers, but these throw the best soundstage and have great imaging. I find them non-fatiguing, but they like lots of power on tap (and I don't listen to loud volumes).

 

[SaSi]

Are you using a KUBE with the 104/2? It is needed to get the full bass extension.

 

[arclight73]

I would take a serious look at the Rotel RA-1572. As mentioned above those KEF's really like power and they would really appreciate the much larger power supply and power increase with the RA-1572.

 

[SaSi]

I was using a Technics SE-9060 (2x110WRMS/4Ω) with my KEF 107 with KUBE. It didn't really sound like it needed more power as the room is medium sized and the volume control was at 12:00 at most.
But I got myself a dbx BX-3 MkII power amp, with an output between 3-4 times as much and although I don't listen to a louder level, transients and peaks are cleaner and leaner, if I'm excused to use this word.
If you normally listen to 1-3W levels, to be able to reproduce peaks effectively, the amplifier should be able to deliver peaks of at least 10x the power. That sounds - and is - easy if 1-3W average output is enough for your application. It is for mine, in the home office system for background music. But for serious listening, once you get into the 10-30W average levels, you start needing a more powerful amplifier or compression will start.
If you use the KUBE, that amplifies the low frequencies, that makes the strain in the amplifier even bigger. And low frequencies need the most current to properly be delivered to the loudspeakers. Even without a KUBE, low frequencies are power hungry. If the amplifier clips gracefully, overload doesn't sound bad but just like the level is inadequate.

At least, that's how I understand it, in plain words and adequate technical validity.

 

[Ross6860]

^^Any idea of the volume level?^^

I typically listen at an average 75-ish dBA, peaks maybe 85-90 dBA depending on material.

I'm feeding them with an ATI 1502 per channel, running in bridged mode.

I have a Kube, but it just collects dust. I've never even hooked it up. I have not had any issues with bass (as in feeling I need more). I should at least give it a try. I've read it may muddy the mid-range and high end.

The KEF 104/2 disappear in the room the way no other speakers do, at least ones I have owned. They may not be my best speakers as far as detail or extension, but may be my favorite speaker to listen to.

 

[Lou G]

I do not have a Kube with my 104/2s but I never felt the need for more bass with them. I agree the 104/2s are not the ultimate in detail but their overall presentation is hard to beat.

 

[twodeko]

Thanks for all the replies!

I'm not using a KUBE since one wasn't available when I bought these speakers used and I really enjoyed them without it. The speakers have decent bass with all of the amps I've tried, however the Rotel integrated seems to have better bass response and than either NAD - both 80 WPC and 120 WPC.

I was interested in the RA-1572 but they didn't have this available to demo and didn't find the Rotel A14 to sound muddy or distort at high volumes, even with classical or other dynamic tracks. With my setup, normal listening levels were < 40% volume and I had a hard time listening above 65 - 70% for extended periods of time.

In the end I decided to purchase the Rotel A14 and return the NAD C368. I'll keep my C370 and swap it back in if I suspect the Rotel is lacking power and regret not demoing the RA-1572