Integrated amplifiers — Line Magnetic Audio LM-216IA Plus

The LM-216IA Plus is an upgraded version of the LM-216IA, the push-pull KT88 integrated amplifier from the Chinese valve specialist Line Magnetic. Where the original LM-216IA offered switchable triode and ultralinear operation, the Plus version is listed with a single rating of 45 W per channel in class AB and adds wireless reception, a motorised volume control and a toroidal mains transformer. Line Magnetic's European arm lists it at EUR 1,599.

Key specs that matter

Four KT88 output valves work in push-pull, two per channel. Line Magnetic states that the preamplifier stage of the Plus was upgraded to Mullard 6CL8A valves and that the KT88s are a version customised by Noble Voice. Frequency response runs from 10 Hz to 50 kHz within 1.5 dB, THD is quoted at 1 percent at 1 kHz with an 87 dB S/N figure. Input sensitivity is 340 mV into 100 kohm. The chassis measures 376 x 345 x 191.5 mm and draws 240 W from a 220 V 50 Hz supply held within 5 percent.

Engineering and use context

The Bluetooth receiver is built on a Qualcomm QCC3024 chip, which Line Magnetic picked for lower power draw and quicker wireless transfer. Volume is set by an ALPS motorised potentiometer from Japan, so the supplied handset can turn the level up or down while the valve circuit stays fully analogue. Wiring is done by hand, point to point, to keep lead lengths short and limit interference between parts. Power comes from what the maker calls a new generation LMC toroidal transformer, intended to cut signal losses and keep current and voltage steadier under load. At the back the loudspeaker connections use carbon fibre terminals isolated by gaskets made of nylon with glass fibre and POM. Despite these changes, the Plus keeps the case size and 19.6 kg mass of the standard LM-216IA, so it drops into the same shelf space.

Pairing

Separate 4 ohm and 8 ohm output taps let the transformer secondaries be matched to the nominal load of the chosen loudspeakers. The high input impedance is easy for valve or transistor sources, whether a disc spinner, a network player or a phono stage, and a phone or tablet can play through the Bluetooth link without any extra box on the rack.

Alternatives

The Line Magnetic LM-211IA is a push-pull integrated amplifier built around four EL34 output valves, with switchable triode and ultralinear operation.