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25 watts Class A or 70 watts Class A/B ?

I understand these days there are many good examples of both Class A and Class A/B amps. To the point that a well designed Class A/B can beat a similar pedigree Class A amp. However my question is in particular related to these two amps:

1. First Watt F5 (Pass Labs)
2. Naim NAP 300

The speaker to be driven is a Tannoy dual concentric Turnberry SE. It is a 93 db sensitive 8 ohm load and in general considered to go well with both high powered and low powered amps.

F5 is a highly purist class A 25 watts design with a robust power supply. It is a push-pull design so it can generally drive difficult loads better than typical single ended first watt models (F3, F4 etc). I have heard the F5 on an Altec horn system and I loved its pure and direct sound.

Naim amps in general has always appealed to me, again because of their very direct presentation. Music has a certain excitement and bounce through them. The NAP 300 is one of their top models and I am sure it will be a very refined amp.

However I will only buy one. Both these amps must be having few fundamental differences in the way they present music considering they are coming from very different designers. Even the topology is different here.

The first question here is, can a 25 watts F5 drive the Tannoys well ? My room size is 200 sqft and I listen to music at reasonably medium to loud levels. I dont play very loud though. I listen to all kinds of music from Mozart to Metallica.

Qualitatively, sound per sound, how do these two amps compare ?
pani
atmasphere's avatar
atmasphere
11,913 posts
 
Just a FWIW: 93 db is not considered high efficiency. It is a moderate efficiency. You are transitioning from moderate to high efficiency about 97 or 98 db.

If the room is small enough or lively enough, I would go with the F5 in a heartbeat- it is one of the best transistor amps made and by that I mean best-sounding. But if you keep running it out of gas it will be frustrating in the long run. Any chance to do an audition?
mapman's avatar
mapman
22,396 posts
 
Obviously the Pass has a lot of upside if it is up to the task in your specific setup and room. So there is some risk with this option, possibly worth taking.

The Naim is a safer bet, and will still likely sound very good!

So if it were me, I would only buy the Pass if I knew I could change afterwards without taking a financial hit. You could buy used, not overpay and resell if needed, or buy from a source with a good return policy. Then if does not work out, you still have good options and little downside other than extra work to change and perhaps a small financial hit, depending.
pbnaudio's avatar
pbnaudio
1,613 posts
 
Don't know where your located, if here in the US you could try one of these out.

Liberty B2B-100

Theres a few reviews out

Good Sound Review

Don't forget to click on the measurement tab, Bascom King performed the technical test of the B2B-100

Positive Feedback Review

And yes I do make them

Good Listening

Peter
bombaywalla's avatar
bombaywalla
1,958 posts
 
So, Peter, what's the deal here (just trying to understand this for myself) - you have PBN Audio manuf loudspeakers & also several amplifiers & then you have Liberty Audio also manuf some power amps??
How does Liberty Audio compare to PBN Audio? Is Liberty Audio the down-market brand?
Thanks.
charles1dad's avatar
charles1dad
10,250 posts
 
Pani,
You have received some thoughtful replies with the inevitable varying opinions. I agree that speaker sensitivity isn't the only consideration, the load in ohms probably is more relevant. Pani my room is noticeably larger than yours and my speakers are 94 db and a 14 ohm load.

I have a 100 watt and a 40 watt push pull amplifiers class AB. Both of these fine amps have been in a 5 year hibernation since the arrival of my 8 watt 300b SET amplifier. It just sounds better and is superior overall (not close).It's very possible that the Tannoy may be more difficult to drive than my Coincident , I don't really know. It's also possible you may simply prefer the presentation of a high power amplifier (I believe that low power amps sound better with an appropriate speaker choice). Lower power may not be what you need to meet your specific goals.
Good Luck,
Charles,
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