A subpoena is a court order. Therefore, it doesn't matter whether you want to show up or not. If you fail to show up, then the court could find you in contempt and issue a bench warrant for your arrest.
You may want to contact the attorney whom requested issuance of the subpoena and discuss this matter with him/her directly.
If you have been subpoenaed to come to court and testify, the party who issued the subpoena obviously believes your testimony will be helpful to their side of the case. If they want to submit at trial something that you said, unless you testify they cannot use your earlier statements, even if recorded, because that would violate rules of hearsay and/or the defendant's constitutional right of confrontation. The parties can, if they wish, agree to use an out of court statement as evidence, but that rarely happens.
Every person has the Fifth Amendment constitutional right against self-incrimination. If there is any possibility that you will be asked a question where a truthful answer might later be used to try to link you to a crime, then you can be excused by the judge. Some judges will excuse a witness entirely, while others will excuse the answering of specific questions, but require the answering of others.
If you have money, hire an experienced criminal defense attorney in your area right away to advise you, and present to the judge your position that you have a constitutional right not to testify. If you do not have money, when you get to court, you might if appropriate tell the judge that you want to exercise your Fifth Amendment right not to testify. If the judge says anything but goodbye, you can ask him to appoint you a lawyer. The judge will either excuse you, or end up appointing you a lawyer, who can properly advise you from there.
The most important thing is that you need to show up. Showing up for court is inconvenient for you, but it is also inconvenient for most people. If people were allowed to decide for themselves whether to come to court and testify, many people would not show up, and a lot of injustice could take place.
A subpoena is a court order, even if signed by an attorney or court clerk instead of a judge. If you violate a court order to appear you can get into trouble for contempt of court or, in some cases, something worse. Moreover, if you are ever arrested for anything the whole rest of your life, your failure to appear in this case will be used against you to set a high bond, or to deny bond entirely. It is best to have a perfect record of showing up for court when required.
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They want you live and in person, you are probably a part of the puzzle and they need your testimony. They can haul you into court but they can't make you testify if you invoke the 5th Amendment, but they may have police who can testify as to what you said. So, you have to show or they will issue a warrant for your arrest, what you testify to or don't testify to is a question you need counselling on, especially if you were involved. I need more information to give you better information, but I believe my learned colleagues have explained this in detail and the decision as to what to do is up to you. If you have been served you are stuck. You have to make a decision and I would reveal all the facts to a lawyer who can help you.
Legal disclaimer: I am not your attorney and we have no attorney/client relationship. This response is submitted for informational purposes only. This is not legal advice, nor is it intended to be taken as such. Anyone considering the above referenced response and should always consult directly with an attorney within your jurisdiction before taking any action based on this, or any other information. This information is provided without any cost and therefore is worth what you paid for it. Again this information does not create any privileged attorney/client relationship and you are cautioned about information you convey to any person in a public forum.
The long and the short of it is that the tape recording is inadmissible hearsay, and the subpoena is an order. You can go to court on your own or have the Sheriff assist you. Your choice.
Disclaimer: This is a general discussion of legal principles by a California lawyer and does not create an attorney/client relationship. This is not intended to be legal advice in your specific case. It's impossible to give detailed, accurate advice based on a few sentences on a website. You should always seek advice from an attorney licensed in your jurisdiction who can give you an informed opinion after reviewing all of the relevant information in your case.