Audio Connections


To connect B2 to loudspeakers you will need speaker leads with 4mm plugs to plug into the B2. We sell 3 metre leads but you can buy or make your own. 4mm plugs are often called banana plugs. The loudspeaker connectors on the B2 are spaced 10mm apart so don’t buy plugs that are wider/fatter than that.

Loudspeakers should ideally be eight ohms but B2 is OK down to four ohms if you keep the volume below the max. The loudspeakers should be rated to handle at least 15 watts RMS continuously. Our BSP50 loudspeakers are rated at 50 watts.

The power amplifier is a bridge amplifier - red and black outputs are both driven - so you cannot connect the two black terminals together and you cannot use the loudspeaker outputs as an input to another amplifier.

The power amplifier is short circuit and thermally protected - if it does shut down just press stop - remove the fault or let it cool and press play again.


You can plug headphones with a small 3.5mm jack into the combined spdif/line out connector. The headphone volume is adjusted by the knob on the front.

Plugging in the headphone will normally disable the loudspeakers (but see the section on Jack Sense below).

The line out connector has shared uses so it doesn’t have a dedicated headphone amplifier or a true line level output for that matter. If you need audiophile quality or have “difficult” headphones then I suggest using an optically coupled headphone amp like this.

Connecting to an amplifier or AV equipment - optical

The best way to connect to an amplifier is optically - but you need an amplifier with an optical input. There are two advantages to optical.

1) The digital “signal” delivered to the amp is exactly what left the Brennan.
2) The equipment is electrically isolated so there is less likelihood of ground loops and other kinds of interference upsetting the amp.

Conversely a traditional analogue electrical connection suffers from - attenuation, frequency response, cross talk, interference and ground loops - but may be adequate especially for short hops.

The optical cable should have a Toslink connector at one end (for your amp) and a 3.5mm plug on the other like this.

Connecting to an amplifier or AV equipment - electrical

Brennan B2 uses a 3.5mm stereo jack and your amplifier probably has twin phono (or RCA) sockets so you will need a cable like this to connect them.

Important - To get the best signal you should turn up the volume on the B2 almost to max - say level 60 - and leave it there. Use the volume control on the final amplifier to get the right listening volume.

Some audio equipment may need a higher signal level than B2 can generate - up to 3.4V pk-pk or a lower impedance say 600 ohms. We recommend using an inexpensive external optical DAC for this.

Sonos Speakers

The B2 can send music to Sonos Speakers on the same Wifi network. You can play different music to different speakers at the same time using the app or web UI.

See this page

Jack Sense

The normal behaviour of the B2 is to disable the loudspeakers/power amplifier if something is plugged into the SPDIF/Line out. It doesn’t matter whether it's optical or electrical.

If you would like the B2 to continue to drive the loudspeakers - because you want the B2 speakers in parallel - then you can disable this behaviour with

Settings -> Jack Sense -> Jack Sense Off

HDMI Audio

B2 can optionally send the sound to the HDMI output. This is a digital signal so has many of the advantages of optical. You can hear the sound on an attached TV and HDMI is being used increasingly by audio equipment.

You must enable the HDMI output using the settings panel - the cog icon - on the web UI.

Using an external DAC

You can use an external DAC like this inexpensive DAC with optical input - £12.99 from Amazon. Optical coupling will help combat any ground loops. You will need to buy the optical cable from us or equivalent elsewhere. Cheap DACs can provide a lower impedance output. Expensive DACs can provide better quality at a price. The DAC volume is not controlled by the B2 volume control.

Four Speakers

There are two ways you could wire the speakers. 1) In series - this will reduce the amount of power you get 2) In parallel - technically this overloads the amplifier and it will shut down - if you play at high volumes - its not serious just press stop and let it cool for a second or two.