Re: First Dance Music / Blown Out Bass in recording
 

When I shoot a reception with DSLRs, I place a mic near the speakers that feeds a signal to an H4n. I use an XLR splitter so I can spread the signal to both left and right, but I run one channel 30-40 dB hotter than the other channel as others have already described.

Then I run a second H4n with a feed from the board, which goes through an XLR attenuator and then a splitter so I can again run one channel 30-40 dB hotter than the other channel.

Then in the edit I can mix between the two H4ns. We have bands at a lot of our receptions, so it's really critical to get the two different sources since usually, not all instruments are mixed in the house system on an balanced level due to the stage volume of drums and other amplified instruments. Additionally, the board feed is usually really dry and does not have much of the crowd cheering when the couple is introduced, at the end of toasts and etc.

So because I need the cable in an XLR, I have an:
RCA to XLR
1/4 inch to XLR
XLR to XLR
XLR attenuator
XLR splitter

When I ask the DJ or Audio Tech if I can get a feed and I have all of the possible cables necessary, I usually receive full cooperation. If the DJ can't get to his outputs on his board because they are buried in a case, I then ask if it's okay to get a feed from the parallel out on his speaker, which is usually XLR or 1/4 inch and in that case, I use the XLR attenuator to drop the volume down to a level the H4n can handle.

Monoprice is a great place to get the cables at a fraction of the price.

Here's a link for the XLR attenuator and XLR splitter that I use.
XLR attenuator| B&H Photo Video

http://www.bhphotovideo.com/c/product/691064-REG/Hosa_Technology_YXM_101_5_YXM_101_5_XLR_Female_to.html

Re: First Dance Music / Blown Out Bass in recording
 

Totally forgot a nice trick.

Most DJ mixer boards have a button to include or not include the microphone on the recording out.

OR, if you don't want his mic work, record out from the headphone jack.