Q: Troubleshoot Sound output for Macbook Pro 2009

What adapter do you have brand/model?

Using How to identify MacBook Pro models and give us a bit more detail?

Also please look About This Mac -> More Info -> System Information -> Audio with the cable/adaptor connected.

A 2009 MBP does NOT support sound via HDMI, only video.  In order to use the MBP as a sound source, you will have to tap the audio output port.  You probably will need a 3.5 mm plug Y connector with RCA plugs on the other ends.

This is an example:

http://www.amazon.com/gp/product/B000I23TTE/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=15355 23722&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000EIOROI&pf_rd_m=ATVPDKIKX0 DER&pf_rd_r=1MSS0KTRDM6JK2WRG63E

Longer length ones are available.

Ciao.

Another option, if you need a multi-channel sound support is to use a Optical cable like -

http://www.monoprice.com/Product?c_id=102&cp_id=10229&cs_id=1022902&p_id=1557&se q=1&format=2

From MacBook Pro (13-inch, Mid 2009) - Technical Specifications (all the other Macs from 2009 also support optical digital audio).

Audio

• Built-in stereo speakers
• Built-in omnidirectional microphone
• Combined optical digital output/headphone out (user-selectable analog audio line in)
• Supports Apple Stereo Headset with microphone