"As a means of avoiding needless duplication and promoting judicial economy, in some instances the preliminary hearing on the charges that give rise to the probation revocation proceeding may be coordinated with the final revocation hearing, in a single proceeding. Either pursuant to an existing blanket cross-assignment to the municipal court, or a specific assignment in a particular case, it sometimes will be possible for a superior court judge to act as a magistrate in conducting a preliminary hearing in the municipal court while conducting concurrently a probation revocation hearing. In this coordinated proceeding, the decision maker charged with the determination whether to revoke probation necessarily would observe the demeanor of those witnesses who testify for purposes of the preliminary hearing, thereby satisfying that component of a defendant's constitutional right of confrontation, rather than attempt to assess credibility from a cold record or defer to the other judge's assessment of the witnesses' credibility." ( People v. Arreola (1994) 7 Cal. 4th 1144, 1159, 875 P.2d 736 [hereinafter Arreola].) In discussing those circumstances which would allow hearsay evidence to support parole revocation, the Arreola court held: "Thus, in determining the admissibility of the evidence on a case-by-case basis, the showing of good cause that has been made must be considered together with other circumstances relevant to the issue, including the purpose for which the evidence is offered (e.g., as substantive evidence of an alleged probation violation, rather than, for example, simply a reference to the defendant's character); the significance of the particular evidence to a factual determination relevant to a finding of violation of probation; and whether other admissible evidence, including, for example, any admissions made by the probationer, corroborates the former testimony, or whether, instead, the former testimony constitutes the sole evidence establishing a violation of probation. Several federal circuit courts have adopted a similar approach, balancing the defendant's need for confrontation against the prosecution's showing of good cause for dispensing with confrontation." ( People v. Arreola, supra, 7 Cal. 4th at p. 1160.)