The fan noise is noticeable, but barely noticable at low listening levels. I've also heard from audio dealers that these amps have a tendancy to overheat,....I've been fortunate enough to find a fan with airflow requirements than the stock fan,..and I also mounted the fan externally which cuts down on the internal echoed fan noise.

Aside from the effort I invested in modifing the amp in regards to the fan/heat situation, I have no complaints what-so-ever about this amp. When I have telephone conversations in my livingroom, the people on the phone acknowledge the clarity and detail of the music! This a sleeper of a product, its unfortunate Sumo Inc. is no longer around. I'm currently deciding whether the Sumo Athena MkII is worth my time, considering I have access to one, but have read no reviews about it and know nothing about it sound or construction....If anyone has ever heard one or has one...Plz e-mail me and let me know if its worth my time.....

I'm good with my hands, so the modifications are of no bother to me...Five Stars...Luv this amp.

Similar Products Used:

B&K...Parasound...Harmon Kardon...Hafler...Musical Fidelity

Amazing Transparency

Noisy Fan

I have owned my Sumo Nine Amplifier for about 6 months now. Do not be fooled by the date listed above because that is the oldest selection they offer. This amp was made in approximately 1986 and offers sound that is difficult to get with $2000-3000 dollar amps. Although nominally rated at 60 Watts into 8 ohms it will do double into 4 so for most applications it has plenty of power (perhaps not with inefficient electrostatics however). This amp is pure class A on the output and it shows. It is smooth, smooth, and smooth but not in the way that people claim tube amps are smooth. No, this is not a warm amp per se, just so damn transparent that you don't get the feeling you are listening to an amplifier at all. THe highs are detailed without a trace of harshness and there is enough bass control and slam to make your toes tap. I compared this amp to many relative expensive used amps, and I have to say I was surprised and shocked at what I heard. One thing that almost made me rate this amp lower than 5 stars was the fan. It really is somewhat annoying but the amp WILL overheat if you disconnect it (I did this but shut it down before things got too roasty). So far I have been unable to find a replacement fan that meets the airflow requirements and is actually quieter. One option I have been considering is to build a different chassis that will allow for more heatsinks and hopefully eliminate the fan but this is a major undertaking that I currently don't have time for.
Fan aside, however, this is an excellent amp that can be had for less than $600 that sonically is as pure as anything I have heard.