Single-ended tube amplifiers tend to appeal to listeners who value circuit simplicity and carefully chosen system partnerships over headline power figures. The BonaWatt Tamesis follows that path, but it does not treat traditional tube design as an excuse to omit modern conveniences. Its all-tube signal architecture is accompanied by a 128-step attenuator, comprehensive remote control, standby operation, trigger outputs and a preamplifier output.
Developed by emerging Polish manufacturer BonaWatt and presented at the Warsaw Audio Video Show 2025 and High End Show 2025 in Munich, the Tamesis is an integrated amplifier for deliberately assembled systems. Its continuous output of 11.5 watts per channel makes loudspeaker sensitivity and room requirements important, while its three line-level inputs keep the source side straightforward. The attraction lies in that combination of focused tube engineering, unusually fine volume adjustment and day-to-day usability.
A focused single-ended Class A architecture
The Tamesis uses a single-ended, ultra-linear Class A output stage built around two KT77 beam tetrodes, one for each channel. Two 6SL7GT dual-triode tubes serve in the preamplifier section, while a 5AR4 rectifier completes the specified tube complement. This makes the Tamesis an all-tube design rather than a hybrid amplifier that combines valve and solid-state gain stages.
Single-ended operation is a purposeful engineering choice. Instead of pursuing high output through multiple power tubes working in push-pull, the Tamesis delivers 11.5 watts per channel continuously at 1 kHz into either 4- or 8-ohm loads. The result is a product whose priorities are clearly defined: it is intended for appropriately efficient loudspeakers and listening situations where modest power can be used effectively.
BonaWatt also specifies its Parabolic Power Bias technology as part of the output-stage design. The available information does not detail the underlying implementation, but the system is documented as a means of optimizing the amplifier’s operating performance. It sits alongside the Class A, single-ended and ultra-linear choices as one of the Tamesis’s central technical features.
Specifications that clarify its intended role
The published frequency-response figures are extensive for a tube integrated amplifier: 6 Hz to 40 kHz at -3 dB, 15 Hz to 31 kHz at -1 dB, and 20 Hz to 25 kHz within ±1%. These are laboratory specifications rather than listening impressions, but they indicate that the circuit has been designed to operate well beyond the conventional audible-band endpoints before reaching its stated -3 dB limits.
The specified signal-to-noise ratio is 94 dB with a ±1 dB tolerance. Total harmonic distortion is listed as less than 2.8% at 1 kHz and less than 4.2% at 32 Hz. Those figures should be understood in the context of a low-power, single-ended tube topology, where output architecture and operating behavior differ from those of high-power solid-state amplifiers.
Input sensitivity is 540 mV for an 8-watt RMS output, while input impedance is 20 kilohms. These figures are useful when assessing source compatibility, particularly for owners using an external DAC, phono stage or line-level streamer. They also reinforce the importance of considering the complete system rather than selecting the amplifier solely for its tube complement or appearance.
An unusually precise approach to volume control
One of the Tamesis’s most distinctive practical features is its 128-step volume attenuator. Adjustment is provided in 0.5 dB increments, with a stated tolerance of ±0.15 dB. This offers considerably finer gradation than a basic low-step selector and should make it easier to establish a repeatable listening level, especially in systems where efficient loudspeakers can make larger volume jumps feel abrupt.
The attenuator uses military-grade resistors and Japanese electromagnetic relays with silver-plated contacts. Rather than relying on a conventional continuously variable potentiometer, this arrangement selects defined resistance values at each step. Its appeal is not simply technical: precise increments can help with low-level listening, comparisons between sources and returning to a familiar setting.
Volume can also be adjusted from the supplied remote control. The handset additionally manages input selection, mute and display brightness. These controls address routine usability without changing the amplifier’s deliberately simple signal-source arrangement. Owners can operate the Tamesis from the listening position rather than treating hands-on adjustment as an unavoidable part of using a traditional tube amplifier.
Connectivity kept simple, but not isolated
The Tamesis provides three stereo RCA line inputs. There is no documented digital input, phono stage or network-streaming section, so each source must supply a conventional line-level analog signal. That makes the amplifier suitable for owners who already have their preferred DAC, streamer or phono preamplifier and do not want those functions built into the integrated amplifier.
A preamplifier output expands the possibilities beyond the internal power stage. It uses a three-pin XLR connector but is explicitly specified as unbalanced, an important distinction for system planning. The connector format should not be interpreted as evidence of a balanced signal path. Subject to appropriate compatibility checks, the output can support system configurations that require a separate downstream amplifier or another line-level component.
Trigger outputs make the Tamesis easier to coordinate with other compatible equipment. Standby mode draws less than one watt, adding a useful contemporary feature to an amplifier whose tube circuit consumes 130 watts in normal operation and may draw up to 220 watts during startup. These details matter in everyday ownership because they distinguish operating power, startup demand and low-consumption standby behavior.
Substantial construction and restrained presentation
At 450 mm wide, 300 mm high and 350 mm deep, the Tamesis requires more vertical clearance than many conventional integrated amplifiers. Its 27 kg weight also calls for a stable equipment platform and careful placement. Prospective owners should account for both the physical load and the ventilation needs normally associated with exposed, heat-generating tube electronics.
The amplifier is offered in black, silver and gold finishes. Its styling is described through a minimalist industrial approach, allowing buyers to choose among three visual treatments without altering the underlying product. The combination of a substantial chassis, exposed tube technology and controlled front-panel presentation positions the Tamesis as a specialist component rather than a compact lifestyle amplifier.
That physical commitment is part of the design’s identity. The Tamesis does not attempt to hide its tube architecture or reduce it to desktop proportions. Instead, it packages a traditional output-stage concept in a chassis equipped for modern remote operation and system control.
Who the BonaWatt Tamesis is best suited to
The clearest audience is the listener building around high-efficiency loudspeakers. With 11.5 watts per channel, the Tamesis should be matched by considering speaker sensitivity, impedance behavior, room size and desired playback level. BonaWatt specifically positions the output for efficient speakers and intimate listening environments, rather than suggesting that the amplifier is a universal partner for demanding low-sensitivity designs.
It should also suit owners who prefer separate source components. Three RCA inputs provide room for a focused analog system—for example, a DAC, an external phono stage and another line-level source—without adding internal digital processing or networking. The preamplifier output and trigger facilities offer some scope for integration, while the remote-controlled attenuator makes the amplifier more practical for regular use.
Conversely, the Tamesis is less naturally suited to someone seeking high output power, numerous inputs, built-in streaming, digital conversion or an onboard phono stage. Its size, weight and power consumption also require more planning than a compact solid-state integrated amplifier. The Tamesis therefore makes the most sense when its single-ended tube topology is a deliberate priority and the rest of the system can be chosen accordingly.
Conclusion
The BonaWatt Tamesis combines a tightly focused all-tube architecture with several thoughtful concessions to contemporary ownership. Its single-ended, ultra-linear Class A output stage, KT77 power tubes and specified 11.5-watt-per-channel output define the amplifier’s specialist character. At the same time, the 128-step relay-controlled attenuator, comprehensive remote, standby mode, trigger outputs and preamplifier connection make it more flexible than its purist circuit concept might initially suggest.
Its strongest documented qualities are not sheer power or all-in-one functionality, but precision, simplicity and purposeful integration. For listeners with efficient loudspeakers, suitable external sources and enough space for a 27 kg tube amplifier, the Tamesis offers a distinctive meeting point between traditional single-ended design and modern control.