I wanted to show a few different solutions for headphone and speaker switchboxes for the HiFiMan Susvara headphones. Everyone knows these are basically the least sensitive headphones on the market so they need to be powered with a speaker amp to sound their best. Speaker amps weren't really made to power 60 ohm headphones, so it's nice to keep them happy with a load closer to what they were designed to output. Also, if you are using multiple amps or one amp for both headphone and speaker duty, it can be pretty annoying to have to get behind your equipment and swap the spades or bananas every time you need to switch. Thus the need for high quality switches that won't degrade the signal.
First use case is a gentleman who likes very minimalist looking equipment, thus the limited printed letters on the front. He wanted to be able to use one amp and switch between his Susvaras and his speakers, so simple single switch operation. The headphone outputs are for low sensitivity (Susvaras or HE-6) and high sensitivity for regular headphones.
This chassis has a 10mm front panel and 2mm for everything else so it has a nice weight to it. This is good for those of you with thick speaker cables. 10mm really has to be machined/milled, most panel mounted parts aren't compatible. In this case we milled so the 4 pin XLRs could be flush mount, and the switch needed some inletting from the back. On the back we have the splendid Cardas CCGS binding posts which are milled copper block covered in gold and rhodium. They're my personal favorite; pricey but you get what you pay for. It also has nice thick aluminum feet with ring dampers but they are hiding underneath. Inside is hand-sleeved high purity soft drawn silver.
Next we have a slightly more budget oriented build that will allow the user to select one of two amps to either power a pair of speakers or the Susvara headphones. It also has a subwoofer output and an RCA is on the back so the user can ground the chassis to a grounding system if desired.
Engraved brass plates provide identification for the inputs/outputs and functions. This unit utilizes a set of EAR isolation feet.
This one isn't necessarily for a Susvara but it allows the user to select between 3 balanced headphone amps and 4 balanced headphones. It features nice Grayhill switches and hand-sleeved high purity soft-drawn silver. The knobs are milled aluminum. The 3 inputs are on the back of the unit. Remember to turn down the amplifiers before switching for two reasons, one tube amps need a load, and two, you could inadvertently switch to a higher sensitivity headphone and the high volume could harm it.
I make a lot of these types of projects but these I found to be some of the more interesting ones. As always you can order a speaker amp to headphone converter that can switch between low and high sensitivity modes, and can switch between 4 pin and 1/4" outputs. This one has a speakON connector for use with a Benchmark AHB2 Amplifier. The Benchmark is a popular choice to use with the Susvaras.
If you are trying to power low-sensitivity headphones via a speaker amplifier, please check out the CBOX at Zynsonix.com. It provides a safe consistent load for your amplifier while delivering the juice your headphones need.
