roadierider

Overall Rating
 5 of 5

Value Rating
 5 of 5

Used product for
More than 1 year

Visitors rate this review
1.00 of 5, 2.00 votes

Price Paid:  $450.00 from Ebay

Summary:
I've been using a SUMO Model Nine amp for my main system for about 4 years now. It is a fabulous sounding little amp! I think solid state "class A" is the way to go if you want a somewhat tube sound without the eventual maintenance issues.

I orig. used a Sumo Andromeda II amp for the mains. Great amp, but overkill on the powerfor my efficient speakers. Now I go thru an active crossover and use the Nine amp down to about 65 HZ . The Andromeda II is now running a homemade NHT driver (#1259?) subwoofer. I quit tinkering after this setup. It sounds great!

FYI, I feed the amps via an AVA "Audio by Van Alstine" hybrid SS/ tube pre amp, then an Audio Control active crossover that I bought about 10 or 12 yrs ago. I think those were the last pieces of gear that I bought new. After that I got addicted to good deals on used vintage stuff.

As far as the fan..... It drove me crazy. I like zero background noise when I 'm listening, so I took the fan and top off and made a new cover. I bought a piece of heavy expanded steel mesh at Lowes. (available in 2 x 2 ft sheets and has 1/2 inch diamond shaped openings). I shaped it perfectly, painted black to match and bolted it on. It looks great and has max open air flow. It gets very hot, but so far it's been fine. The up side with a class A amp is that they make great space heaters in the winter months....:-)

BTW, It's 60 wpc "class A", not 650 wpc, as the above heading states.

Jeff

Strengths:
Open, airy, floating mids and highs. Great low, tight bass too.

Weaknesses:
Fan noise. See above. I remedied that problem. I figured at the price I paid, I'd remove the fan and chance the overheating problem. So far, 4 years later it still works flawlessly.

Might not have the power needed for big inefficient speakers if you are into turning them up loud and running them full range. It has more than enough muscle for my setup.

Just keep the drunk at your party away from the volume control if you have inefficient speakers.

Similar Products Used:
A bunch of toys over the years.

dynalead

Overall Rating
 4 of 5

Value Rating
 4 of 5

Used product for
More than 1 year

Visitors rate this review
5.00 of 5, 1.00 votes

Price Paid:  $1000.00 from The Listening Room

Summary:
Bought 2 Sumo Nines when they were first produced (early 80s?). Have been using since then driving Dahlquist DQ10s, Magnapans, and now Sound Dynamics 300ti. Amps were stored for a time in basement that flooded. Cleaned them up, still operating! Only problem was tendency to blow the power rail fuses. Fan was noisey. I removed the fan and the case. Amps have been operating like this for years without a problem and no overheating. Keep children and cats away!

Strengths:
Great sound stage and imaging. Very smooth sound (Class A?.)

Weaknesses:
Would like a bit more power occasionally. Always hot because I leave them on all the time (helps heat the room in the winter.

Similar Products Used:
Ampzilla

jwsb

Overall Rating
 4 of 5

Value Rating
 5 of 5

Used product for
Less than 1 month

Price Paid:  $400.00

Summary:
I am really quite surprised at that I found any reviews on this product at all! I know that Sumo's been out of business but could still have some of the Bongiorno descendants out there; most notable of his products would have to be the Sumo Nine and 9+. Technically, I could not dare to axplain what Class A really means. I saw this unit on the shelf collecting dust for more than a year at a friends shop and got a bit curious. Started surfing for reviews: Ditto. Except some impression that the amp has quite a cult-like following. How does it sound? After taking the unit home for auditioning matched with music reference RM5 Tube pre and Soliloquy 5.0 speakers. The result was impressive. It seem to cough up a bit and sounded steely at first (probably the result of being in storage too long) but later bloomed and opened up after a few hours. Definitely an excellent performer. After a few hours details seemed crisper and the amp started to breathe. Despite it's heavy looks, the sound seems airy and transparent resulting in less fatigued listening. The sound stage was also better than expected from an SS. Would recommend this Amp for anyone who wants to get into hi-end sound. Don't let looks and age fool you.

Strengths:
Airy/transparent, delicate

Weaknesses:
Didn't have the low end punch you would expect from SS. Could someone send me the Power ratings on this thing?

Similar Products Used:
AMPS: Ambient Tech Tube Amp(40wpc EL34 Ultralinear), QUAD 405-2, Adcom 545, Hafler XL600, DH220, P230, NAD 3020B, Ambient SET (RCA 6AS7 Single Ended Parallel) Speakers: Soliloquy 5.0, Magnepan SMGC, B&W 604, Epos ES14, Systym 935, Tannoy M2,B&W 201 Prism

Price Paid:  $500.00 from Accurate Audio, Sant

Summary:
My Sumo Model Nine Class A amplifier has given me more than 20 years of high performance. It has also been reliable beyond belief. James Bongiorno says he never had an output transistor fail in a Sumo Nine, and I believe him. How many amps can remain this trouble free over more than 20 years? I do not intend to replace this beauty. It delivers 120 watts into the 4 ohm load presented by my Dynaudio Audience 42s. What more would you ever want when driving a pair of Audience 42s? The sound is both sweet and extremely coherent. Smooth. The greatness of the Sumo Nine revolves around its ability to recovery gracefully whenever it is overdriven. Your ears never hear any clipping distortion, because the amp is so effortless in its reovery. It never loses a step. There is no way i can buy a better amp for the Dynaudios. The soundstaging is phenomenal also. This amp may be the all time champ in terms of bang for the buck. System includes Rega Planar 2 with Blue Point, Arcam Diva 62T CD, Adcom GTA 500 preamp and tuner.

Strengths:
Extremely smooth from botttom to top. Great ability to recover from clipping. Excelent soundstaging. Very musical.

Weaknesses:
Absolutely none. The most reliable amp you could ever want.

Similar Products Used:
Had a Yamaha CA 1000 decades ago. Nice integrated. And many of the infamous Quatre Gain Cells. Blowup champions of all time.

Price Paid:  $550.00 from Private

Summary:
I read a number of glowing reviews of this amp and jumped at the chance to purchased the Nine Plus when it appeared in the local classifieds. Compared to the NAD 208THX and Harman Kardon PA2200 I owned previously, the Sumo delivers delivers improved definition between instruments, and is sweeter sounding. A number of recordings I considered harsh sounding prior to buying the Sumo became listenable & enjoyable. Considering that the amp can drive a pair of Magnepan's to reasonable sound levels I don't think anything used compares in this price range. My low budget system: *Sumo Nine Plus Amplifer *Modified PAS 3 tube pre amp *Musical Fidelity X24 DAC *Yamaha 555 CD Player *Magnepan SMG's *Energy XL8 Sub

Strengths:
Clear, sweet, articulate sound

Weaknesses:
The fan which is bothersome even after replacing the stock unit with a superior quality (lower db) ball-bearing fan

Similar Products Used:
None