The VA-105-SW is a five input passive switch with a single output.  It provides three RCA inputs and independent front and rear 1/8" TRS aux inputs.  A dedicated grounding terminal is provided for the chassis which is decoupled from all the signal grounds.

Switching is accomplished using a Grayhill series 71 rotary switch that provides excellent crosstalk performance with an pleasant ergonomic.  Both the signal and ground are switched for each input, eliminating potential ground loops.  The VA-105-SW is housed in the same small footprint case as the VA-221-SI with a similar classic look.

INSERT CROSSTALK PERFORMANCE HERE

The VA-221-SI is the fourth generation of Vectis Amplification's headphone amp. The topology utilises the incredible Burr-Brown OPA2134 amplifier. Some of the notable features are:

• Battery or wall power
• Buffered output
• 1/4" and 1/8" output jacks
• RCA, 1/4" or  1/8" input jack
• Switchable signal attenuation of -6 dB
• Switchable gain of 10 or 20 dB 
• Stereo or Mono switch
• Switchable sound-stage option
• Small footprint in a classic look

The VA-221-SI is a single input device with three choices of input.  The priority is 1/8" TRS > 1/4" TRS > RCA.  Only a single input should be active during use.

The sound-stage is designed to reduce listener fatigue by bleeding a small portion of the signal across channels.  

Because all sources have different output levels, the VA-221-SI is designed with a signal attenuation switch which is useful to attenuate the input signal when high output devices are used.  A typical 0.3 V_RMS signal will not require any attenuation but a professional output level of 1 V_RMS will benefit from the 6 dB cut at the input.

The amplifier works well with a range of headphone impedances.  I currently use it with Sennheiser HD 280 PRO headphones at 64 Ohms and beyerdynamic DT 990 Pro at 250 Ohms.  The sound is slightly reduced with the higher impedance headphones, but still more than loud enough to hurt.

Schematic