Michi P5 preamplifier and S5 power amplifier

Solid-state power amplifiers,
Solid-state preamplifiers
Rotel Michi P5,
Rotel Michi S5
Michi P5 preamplifier and S5 power amplifier

Rotel is one of those companies that doesn’t often grab the headlines much these days yet it has a heritage stretching back over 50 years. In the late 1980s, its entry level integrated amplifiers had a great reputation for delivering better sound than most thanks in part to UK design input that gave it an edge. This approach was duplicated by other Japanese brands with the Pioneer A400 being a notably successful example. In the mid-1990s, Rotel introduced some rather more lavishly built models that it dubbed Michi. These electronics had wooden end cheeks and resembled Japanese high end to a far higher degree than anything seen in its range before. 

Last year, three new Michi models were introduced that are devoid of the Rotel brand and have distinctly different styling. They are also enormous. Both physically and in terms of mass, the S5 stereo power amplifier weighs in at nearly 60 kilos which is ‘big boned’ even for 500 Watts per channel. Yet its sleek styling does not quite match the muscle amp expectations that this figure suggests, neither for that matter does its sound but I’m getting ahead of myself. The weight is largely down to the power supply, which is dual mono like the rest of the amplifier and uses the largest bulk foil capacitors I have yet encountered. Even an image of the internals from above doesn’t really hint at the true girth and height of these things, but when you consider that the 2,200 Volt-Amp toroidal transformers are contained in the boxes marked Michi it gives a better idea of the scale than the 47,000 uF rating for each, unless you’re an engineer. The black aluminium extrusions on either side are heat sinks; square section tubes that have 16 high-current output transistors on the outside and fans to keep air moving. This is a slightly controversial approach in high end audio but these are extremely quiet fans, I did hear them once or twice but only when they switched off and there was no music playing.

They succeed in keeping the large heatsinks on the sides of the case relatively cool or at least they did at the levels I was using them, if you really hammered the amp into some ‘deaf’ speakers all that metalwork might come in handy. Like the early Michi amps this has had some UK design input, this time from long-time associate Bowers & Wilkins’ research and development team in West Sussex. The styling is also British courtesy of Goodwin and Hartshorn who work on loudspeakers for Bowers, they have made the back panel a lot more coherently arranged than usual with inputs above output connections and attractive extrusions on the cooling outlets. The glass front panel looks a little plain without its full set of landing lights in shape of the elaborate graphic display; you can run it like this but there are a variety of things it can show including power output in graphical form with the option to zoom into the meters so that you can see some movement even at lower outputs. There are various functions that can be changed in the display including auto power off time, display brightness etc. Changing the display is done with an RF remote handset, the same handset that controls the matching P5 preamplifier but fortunately careful pointing means you can change the power amp without upsetting the pre.

Connection to the preamp is via balanced or single ended cables and speaker connections can be made to either or both of the terminals for each channel, enabling easy bi-wiring should that appeal. There’s also a trigger connection for the preamp making it easier to switch both on and off with a single button.

The P5 preamp has what can only be described as a wealth of features, including but not limited to a digital to analogue converter, MM/MC phono stage and Bluetooth reception. It even has tone controls and supports MQA, not to mention line level inputs on RCA and XLR connectors. There might be a more fully equipped stereo preamplifier on the market but not at this price. If I were to nitpick I’d say it’s a pity there’s no load adjustment for the MC input and perhaps some filter options for the DAC but this is being churlish given that it not only has sub and line outputs as well as digital and headphone outputs, and a USB A connection for charging purposes. There’s also an RJ45 socket but this is for network installation rather than streaming. The display allows for a huge variety of configuration including input naming, setting an input for AV bypass, balance and signal sensing. The only apparent omission is gain setting for individual inputs.

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