Instruction: Using the product's title, description, features, price, and brand, identify and retrieve the values associated with a specified set of target attributes. Output the extracted values along with their respective sources (e.g., title or feature) indicating where each value was found.

Input:
Product title: CERWIN VEGA HED3600.2 600-Watt 600W 2-Channel 80X2 4-Ohm Power Amplifier
Product description: CERWIN VEGA HED3600.2 600-Watt 600W 2-Channel 80X2 4-Ohm Power Amplifier
Product feature: CERWIN VEGA 600W MAX 2CH 80X2 @4 OHM, CERWIN VEGA 600W MAX 2CH 80X2 @4 OHM, CERWIN VEGA 600W MAX 2CH 80X2 @4 OHM, 600W Max 2Ch 80X2 4 Ohm
Product brand: Cerwin-Vega
Target attributes: Number of Channels
Answer: attribute: number of channels
value: 2-channel
source: product description
attribute: number of channels
value: 2ch
source: product feature
attribute: number of channels
value: 2-channel
source: product title