Pure Class-A Amp under $2000 (USED)

No one is mentioning Plinius SA 100 ? This amp can even powered my Andra Eggleston and it’ redefine Class A category per Stereophile review.

Classe Audio real class A amplifiers are : 

DR-2, DR3, DR3-B (25 Watt - 65lbs.)

DR3-VHC (45Watt - 99lbs)

Hello 8586,

How are you.

You wrote, " I think the wattage range between 30-60WPC for Class-A is powerful and popular".                                                                                                                                   I have no idea what "popular",  has to do with the price of tea in China when it comes to anything, let alone amps. Best to look at the spec data on your Venere's.                   

Sensitivity: 88dB. Nominal Impedance: 6 ohms. Suggested amplification: 50W-200W. These are relatively inefficient/power hungry speakers, that will inevitably "clip" an under powered amplifier. The maker recommends 50-200W. I'm not saying I'm 100% correct on this, but in the name of safety a good rule of thumb is to add 50+200=250, divided by 2 = 125watts. Although they "do" over lap, do not confuse power with volume/dB, think more along the lines of authority as well as head room.

Therefore if you're bent on a pure Class A amp, take heed from (pwerahera) suggestion concerning the Krell KSA 150 and 250, or (jeffseight's) suggestion on a Threshold. Someone wrote that these amps might be overbearing. You did say that a different Pre-amp was in the cards. For approx $2G's, a good tube Pre-amp (VTL Ultimate, ARC-SP8, Audible Illusions Modulus, or an Ampex 402) will get a tiger amp to purr. If tubes aren't your thing, a Classe' Audio DR5 is a good SS alternative that blends well with a pure Class A amplifier.

Enjoy the music.

I’m not saying I’m 100% correct on this, but in the name of safety a good rule of thumb is to add 50+200=250, divided by 2 = 125watts.

@thehorn You’re likely not correct on this. Understand that you’re conveying general guidelines, but general guidelines are just that and don’t apply in all situations, and this is one of them. For one, the OP is looking for a Class A amp, which out of the box affects how many Watts are required as they mostly double power into 4 Ohms and given their more robust power supplies can provide plenty of headroom even above that. Then, there’s the speaker specs. Using stated specs can be indicative but not always determinative. Case in point, here are JA’s actual measurements of the Venere 2.5 whose stated specs are near identical to the 2.0…
“The Sonus Faber’s voltage sensitivity is specified as 89dB/2.83V/m; my estimate was a little lower than that, at 87.7dB(B)/2.83V/m. The impedance is specified as 6 ohms; the Venere 2.5’s impedance magnitude and electrical phase, plotted against frequency, are shown in fig.1. There is quite a large variation of impedance with frequency, the magnitude remaining below 6 ohms for most of the midrange and bass but staying above 9 ohms for the entire treble region. Though there is a minimum value of 3.45 ohms at 111Hz, the phase angle is extreme only when the magnitude is high. The Venere 2.5 will not be hard to drive.”

Further, I had the 2.5 in my system and will attest they were not hard to drive at all, and my 100Wpc Class A/B amp drove them to very loud levels without even nearly breaking a sweat. And I’d have actually NO reservation saying a 50Wpc Class A amp would be more than sufficient to drive the Venere 2.5, which is why I recommended the Clayton S50 would be a great choice here. I’d even say something like the Pass XA30 @ 30Wpc would be perfectly fine because, as Pass amps are conservatively rated, it’d have more than enough juice to drive the 2.0. Point being, using top-level, basic specs without looking further under the hood can lead to misleading conclusions despite whatever good intentions were involved.

soix Some valid points, most I would agree with, some you’re off the mark by taking points out of context.

You’ll note for DK8586’s benefit (+ others), I used the term "relatively" inefficient/power hungry speakers,

(S/F Venere: Nominal Impedance 6Ω, Sensitivity 88dB). Now for the sake of correlating lets use an apples to apples example, (ProAc D2: Nominal Impedance 8Ω, Sensitivity 88.5db). (Focal Sopra N°1, Nominal impedance 8Ω, Sensitivity 89dB). Now the (Coincident Triumph Extreme II, Impedance Flat 8Ω, Sensitivity 94dB)!

So as you can see yourself soix the S/F Venere’s are "relatively" hard to drive. Now that’s cleared up lets move on.

Your quote "a Class A amp, which out of the box affects how many Watts are required as they mostly double power into 4 Ohms". Where are you at on this comment soix? Mind you lets not be over critical.

1st of all, regardless if it’s an A/B amp or a pure Class A amp, any good quality amplifier doubles in power when it’s impedance is halved. Eg: 100W into 8Ω, 200W into 4Ω, it is not what defines a Class A amp.

2ndly 50watts is 50watts, regardless if it’s an A/B amp or a pure Class A amp. There are no magic watts for Class A amps. They sound different because they run flat out, making them faster and ...... warmer?

Now I’ve got to give you credit on two points. One, the recognition of Nominal Impedance. Two, the observation of higher than rated impedances at certain frequencies. The term Nominal Impedance recognizes that values fluctuate with dynamics, so a speaker that’s rated at 6Ω may drop down to 3.45Ω when reproducing low octive notes and/or sustained crescendos. (How Israel Blume over at Coincident gets a dynamic speaker to operate at 8ohms FLAT is by me). The second point, that impedances at certain frequencies rise, is new to me! So I’ve learned something. Thx.

Reading further into your text, unwittingly you seemed to have reinforced my point. "Further, I had the 2.5 in my system and will attest they were not hard to drive at all, and my 100Wpc Class A/B amp drove them to very loud levels without even nearly breaking a sweat". Well of course you didn’t have any trouble driving you Venere’s soix, when the impedance drops your A/B amp was pulling close to 200watts.

Now you say "And I’d have actually NO reservation saying a 50Wpc Class A amp would be more than sufficient to drive the Venere 2.5, which is why I recommended the Clayton S50 would be a great choice here". Well where’s the correlation between your 100Wpc A/B amp & an S50 Clayton soix?

If I may, let me share my experience with 6Ω speakers & Class A amps. Class A amps run hard, that’s why they’re hot, that’s part of their charm/ethos. Back in the 80’s-90’s a company called Sumo made a fantastic Class A amp that in my area got paired up a lot with low impedance Infinities. (Not implying the Venere’s are in the same boat). They often went up in smoke. Conversely, Mark Levinson made ML-2’s mono blocks that could drive a bus all day and not break a sweat. How an S50 Clayton holds up I would not presume, but Class A amps can be dodgy.

I used a Classe’ Audio DR3, 25Wpc, to run a pair of SB-E 100’s (37Hz to 22kHz. Impedance 6Ω. Sensitivity 95dB). They were used in a 15x25x7.5 room. The DR3 was the sweetest sounding amp you could imagine, and even though the SB-E 100’s were vastly more efficient than Venere’s, it did not have the power to fill a room of that size with the necessary SPL’s I was after, so it had to go. My point is this.

The lesson I learned is that all things being equal, it’s better to have power in reserve than not enough.