Performance evaluations, for bit error rate (BER) and power penalty, are performed for DC coupled burst mode (BM) receivers in the presence of both amplified spontaneous emission (ASE) noise and interchannel crosstalk. Such BM receivers acquire the threshold from preamble bits, so the threshold is a random variable, because of contamination by noise and crosstalk. Here such a crosstalk contaminated threshold is described using a moment generating function for the first time. This facilitates the first use of Chernoff bound, modified Chernoff bound and saddle-point approximation techniques for BM reception under these conditions. A Gaussian approximation (GA) is also calculated. Results for an optically preamplified receiver indicate that the overall penalty (threshold acquisition penalty in the presence of crosstalk (and ASE)) exceeds the straightforward summation of the separate crosstalk and threshold acquisition penalties (in dB) and while this difference is particularly pronounced for the GA it remains significant for the other techniques. Furthermore, the GA is seen to be more pessimistic in BER compared to the other approaches and less accurate (as it exceeds an upper bound). Relative to the other techniques, the penalty predicted by the GA is optimistic for low crosstalk but pessimistic for high crosstalk.