Accuphase amplifier choice

@fire_water 

You can use bananas no problem. 

Good to know - thanks

@westcoastaudiophile 

@milpai +1 "I would go with an Accuphase Class AB amp rather than a Class A amp"

As you would know, this is true purely for my not-so-efficient speakers. If I had a 95+ db efficient speakers then the A-48S would be no brainer. But after reading a lot of user experiences and seeing a lot of Accuphase videos and finally going back and forth on AI, I have come to the conclusion that Accuphase Class A are definitely warmer compared to the Class AB. And I really do not need more warmth in my system.

@fire_water "and I can tell you that Accuphase Class-A amplifiers are in a league of their own and the majority of time and with appropriately matched speakers, Accuphase Class-A amplifiers operate as pure Class A. "

what is "appropriately matched speakers”?

again, Accuphase class A amps are biased warmer than AB (higher idle power), and have wider class A mode full power range, but only if speaker impedance is higher than 8 Ohms (re) across all frequencies.. 

..I do have two Accuphase amps, AB and A, A class one sound warmer at 10W+ power vs AB.. I understand as you don’t have any Accuphase amps in your setup now..?

@fire_water , @westcoastaudiophil,  I posed this question to AI and below is the response:

Short answer:
Yes, Accuphase’s “Class A” amplifiers (like the A-series, e.g. A-48, A-75, etc.) are true Class A designs within their rated power range — but they are heavily biased so that they operate in pure Class A up to their full rated output into 8 Ω, and transition smoothly toward Class AB beyond that.

Here’s what’s going on technically

• Class A operation means the output devices (transistors) conduct current throughout the entire signal cycle (360°), so they never fully turn off. This eliminates crossover distortion but wastes a lot of power as heat.

• Class AB means the devices conduct more than half the cycle but less than the full 360°, improving efficiency but introducing potential crossover distortion.

• Accuphase’s “pure Class A” line is biased so that the output devices conduct continuously for the rated output — for example:

  • The A-48 is rated at 45 W/8 Ω in pure Class A.

  • It will remain in pure Class A up to that point, but can deliver higher peaks (around 90 W or more) because of its headroom. Beyond the rated point, it behaves like a Class AB amp, meaning it leaves Class A operation smoothly rather than abruptly clipping.

• Accuphase achieves this with very high idle bias current and sophisticated thermal management. You can confirm this by noting their heat output — these amps run hot even at idle, a hallmark of true Class A biasing.

In short

Conclusion:
Accuphase’s Class A amps are genuinely Class A within their rated range — not just “high-bias AB.” Their engineering and thermal performance confirm that. However, they’re designed sensibly so that they can exceed that range without distortion by sliding into AB operation.

Would you like me to show you some measured bias current or power consumption data from bench tests (like Stereophile or Audio Accessory reviews) to illustrate this?

@westcoastaudiophile 

I currently own an Accuphase A-48S as I previously mentioned and I thoroughly enjoy it!  This is the best amp I've ever owned but I will upgrade to the Accuphase A80 sooner than later. How, when or even if the A48-S Class-A operates in Class AB is beyond me,  but I can definitely tell you that I can hear a sonic difference and this difference compelled me to purchase this A48-S.  It sounded great with the Fyne Vintage 15 and I'm enjoying it with my LaScala AL5 spkrs and that's all that really matters at the end of the day.