Unlike Spanish natives, Mandarin speakers tend to produce the Spanish lexical stress contrast by manipulating pitch rather than other prosodic cues such as duration. However, the perception of Spanish lexical stress remains less clear. This study examines Mandarin speakers’ cue-weighting strategies in perceiving Spanish stress and investigates how musical perception aptitude and auditory processing abilities affect cue-weighting. Twenty-two L1 Mandarin speakers with advanced Spanish proficiency and 19 Spanish natives participated in a stress perception task, which involved identifying strong-weak and weak-strong lexical stress patterns. The pitch and duration ratio of the target word’s vowels were manipulated (7 steps each). Musical perception aptitude (i.e., accent, melody, rhythm, and pitch) and auditory processing abilities (i.e., duration and pitch) of Mandarin speakers were also assessed. Results show that Mandarin speakers rely more on pitch than duration to identify Spanish lexical stress patterns, in contrast to Spanish natives (duration > pitch). Additionally, only musical accent perception skills significantly predicted Mandarin speakers’ cue-weighting, with higher musical accent scores correlating to larger weighting on pitch cues. The results suggest that even advanced learners exhibit L1 transfer in prosody to L2, and musical perception skills may play a role in L2 prosodic acquisition.