The valve amplifier market is best known for its big pre-amplifiers and power amplifiers. With a few notable exceptions, the slimline convenience afforded the user of solid-state integrated amplifiers is difficult to find. When one wishes to introduce the flexibility of a remote control to the equation, you can count the number of products available on the fingers of one hand - and still have some fingers left over afterward.

Never one to back away from an undefended marketplace, the champion of value-added high-end tube audiophillia, Golden Tube Audio, has finally announced the launch of its new £1,000 SI-50 remote controlled line-level only integrated amplifier, first mentioned in the December issue of Audiofreaks News. This fully-function-laden amplifier has all the convenience of an integrated amplifier with the sound quality normally found in more hair-shirt designs. And it looks superb, too.

At the heart of the SI-50 beats a superbly designed and rugged push-pull Class AB power amplifier stage. This uses four premium-grade EL34 power tubes and two multi-layer ultra-wide-band-width output transformers to deliver a healthy 50 Watts into each channel. This is partnered by a high quality line stage valve pre-amplifier. The line stage has three RCA phono inputs, comprising two line inputs and a tape loop.

Aside from the quartet of EL34 tubes, the remainder of the tube complement in both the pre and power amplifier stages use high quality premium-grade 12AU7 tubes. This makes changing the tubes very easy without any chance of accidentally plugging the wrong tube in. This becomes especially easy as the amplifier has a unique Tube Failure Mode. When a tube fails, the SI-50 automatically turns off, save for a blinking LED to show the user exactly which tube needs replacing.

Manual bias of valves is a thing of the past with the SI-50's proprietary Fuzzy Logic bias control. The amplifier contains a microprocessor which controls and monitors the bias voltage constantly making for the ultimate in accurate tube bias.

The rest of the internal component listing is highly specified. Like all Golden Tube Audio products, the SI-50 sports high-quality WIMA capacitors throughout the signal path, a computer optimised printed circuit board fitted with ceramic tube holders and a pair of heavy-duty power transformers to match the output transformers listed above.

Externally too, the amplifier mixes high technology with high-end sound quality. The three inputs can each be set to passive or active line stage mode to match differing input voltages. It also immediately solves the active vs. passive preamplifier debate - you can get both with the SI-50.

These active/passive settings are then stored in a memory so that you do not have to reset the settings every time the amplifier is switched on.

The solid aluminum machined remote is far more rugged than one would expect at the price. This can be used to select the three line sources, adjust the volume, mute the amplifier and can switch the amplifier on and off. This power switch is a three-position affair allowing the amplifier to be switched into Standby mode.

Among the unique features of the SI-50, who would have thought that a simple balance control would also be revolutionary. Conventional balance controls use a single potentiometer which is generally of lower quality than the volume pot with all the sonically deleterious effects such a pot entails. It is also impossible to get the gain levels of the two channels exactly correct. Golden Tube Audio eschew convention once again, this time in favour of individual left and right fine gain adjustment controls.

Like most remote-control amplifiers, the amplifier has a motorised volume control, complete with a illuminated LED on the solid aluminium knob. Unlike most remote-control amplifiers, however the SI-50 uses a high-quality 25mm Alps control of extremely high quality.

If you are content with buying a system now, safe in the knowledge that you are unlikely to upgrade it in the future, the SI-50 is the amplifier for you. If, however you feel that you may want to upgrade to a pre/power amplifier combination in the future, then the SI-50 is still the amplifier for you. Why? Simply because Golden Tube Audio have placed two pairs of phono sockets on the rear of the amplifier which enable it to be effectively converted to a line-level preamplifier or power amplifier and allow you to add whatever you like in the future.

Even the fit and finish of the amplifier is first-rate. It uses the 3/8" solid aluminium front panel to match that solid aluminium knobs that have become a de facto standard with Golden Tube Audio. As have the gold-plated RCA inputs and five-way speaker binding posts. All of which accounts for the 35lb net weight. The amplifier is finished in the company's standard brushed gold livery with the option of a special black finish to order.

The SI-50 continues in the Golden Tube Audio tradition for making astounding products at surprisingly ordinary prices. As more high-end companies make valve integrated amplifiers, the SI-50 will still lead the field for value.