In Barn for Review: Riviera Labs APL10 Preamplifier & AFM25 Monoblock Amplifiers (a new TM chapter)

Some of you may be thinking, “It’s about time!” I agree!

I’ve been thinking about reviewing separates—preamplifiers and amplifiers—for some time. But it never felt…right. Part of my unease had to do with what amounts to the near random nature of reviewing a preamplifer from Company A with an amplifier from Company Z, or an amplifier from Company X with a preamplifier from Company H. Hmm.

So here’s the plan—I’m going to be reviewing separates—preamplifiers and amplifiers—but only from the same company. Seems to me this is how most people shop and it eliminates any question of inappropriate pairing.

And I can think of no better place to begin than the Riviera Labs APL10 Preamplifier and AFM25 Monoblock Amplifiers.

The APL10 Pure Class A Tube Preamplifier has three unbalanced and one balanced input with a two pair of unbalanced outputs. The review unit came with a pair of NOS RT ECC82 / 12AU7s in place.

The AFM25 Pure Class A Hybrid Mono Power Amplifiers offer 25 Watts of hybrid Triode (12AU7/ECC82), Bipolar Junction Transistor/Mosfet power. A pair of NOS Brimar 12AU7s were installed in each, with the stock JJ ECC802S Gold tubes safely tucked away in their boxes.

Like the Riviera Labs Levante Integrated Amplifier I reviewed (and loved), the Riviera separates follow the same design path. From the company:

  • The Zero Overall Feedback and the minimum use of local feedback, when absolutely indispensable, is the first solution to reach the desired distortion behavior.
  • The use of the A class in all stages is the logical consequence: we need to have the maximum linearity without “tricks”.
  • The hybrid solution is the next logical consequence: the triode is the best voltage amplifier and, mostly in a s.e. configuration, it offers a “natural” distortion shape, very close to the required one. Silicon devices (and specially Mosfets) are the best choice to handle power and low impedance; if properly used and driven, they can offer a good distortion shape too. In the topology adopted they also give the desired output impedance.
  • Protection circuits damage sound. In our thinking this is a fact. So… no protection circuits (only fuses on PSU rails). Consequently a real large dimensioning, not for appearance (coke-like capacitors…) but in the real key points (PSU, transformers, power devices). A secondary consequence is the need for an adequate mechanical dimensioning too.
  • Accurate PSU design. 2 transformers and 5 separate PSU. The tube PSU is PI-filtered and stabilized (with a MOSFet); in the audio power PSU stage there is a PI filter too and the distributed capacitance: instead of 2 big-and-slow capacitors, many little-and-fast capacitors, with the last ones extremely close to each power device.
  • There was a long and accurate musical and bench optimization (with continuous shift from the bench to the listening room and vice versa).
  • Mechanical and “physical” manufacturing with a quality level of a laboratory instrument and a made in Italy design.

Stay tuned for the fun part.


Riviera Labs APL10 Preamplifier
Price: $17,500

Power 25W / 8 Ohm
Zero Feedback
Pure “Class A”
Hybrid design (Triode, BJT, Mosfet)
1 RCA Unbalanced input
1 XLR Balanced input (true balanced)

AFM25 Monoblock Amplifiers
Price: $32,800/pair

Power 25W / 8 Ohm
Zero Feedback
Pure “Class A”
Hybrid design (Triode, BJT, Mosfet)
1 RCA Unbalanced input
1 XLR Balanced input (true balanced)
Dimensions: 26×43.5×14.5h cm. Weight: 14.4 Kg

Company Website: Riviera Labs
US Distributor Website: Tone Imports